Input File Description

Program: pw.x / PWscf / Quantum Espresso (version: 6.0)

TABLE OF CONTENTS

INTRODUCTION

&CONTROL

calculation | title | verbosity | restart_mode | wf_collect | nstep | iprint | tstress | tprnfor | dt | outdir | wfcdir | prefix | lkpoint_dir | max_seconds | etot_conv_thr | forc_conv_thr | disk_io | pseudo_dir | tefield | dipfield | lelfield | nberrycyc | lorbm | lberry | gdir | nppstr | lfcpopt | monopole

&SYSTEM

ibrav | celldm | A | B | C | cosAB | cosAC | cosBC | nat | ntyp | nbnd | tot_charge | tot_magnetization | starting_magnetization | ecutwfc | ecutrho | ecutfock | nr1 | nr2 | nr3 | nr1s | nr2s | nr3s | nosym | nosym_evc | noinv | no_t_rev | force_symmorphic | use_all_frac | occupations | one_atom_occupations | starting_spin_angle | degauss | smearing | nspin | noncolin | ecfixed | qcutz | q2sigma | input_dft | exx_fraction | screening_parameter | exxdiv_treatment | x_gamma_extrapolation | ecutvcut | nqx1 | nqx2 | nqx3 | lda_plus_u | lda_plus_u_kind | Hubbard_U | Hubbard_J0 | Hubbard_alpha | Hubbard_beta | Hubbard_J(i,ityp) | starting_ns_eigenvalue(m,ispin,I) | U_projection_type | edir | emaxpos | eopreg | eamp | angle1 | angle2 | constrained_magnetization | fixed_magnetization | lambda | report | lspinorb | assume_isolated | esm_bc | esm_w | esm_efield | esm_nfit | fcp_mu | vdw_corr | london | london_s6 | london_c6 | london_rvdw | london_rcut | ts_vdw_econv_thr | ts_vdw_isolated | xdm | xdm_a1 | xdm_a2 | space_group | uniqueb | origin_choice | rhombohedral | zmon | realxz | block | block_1 | block_2 | block_height

&ELECTRONS

electron_maxstep | scf_must_converge | conv_thr | adaptive_thr | conv_thr_init | conv_thr_multi | mixing_mode | mixing_beta | mixing_ndim | mixing_fixed_ns | diagonalization | ortho_para | diago_thr_init | diago_cg_maxiter | diago_david_ndim | diago_full_acc | efield | efield_cart | efield_phase | startingpot | startingwfc | tqr

&IONS

ion_dynamics | ion_positions | pot_extrapolation | wfc_extrapolation | remove_rigid_rot | ion_temperature | tempw | tolp | delta_t | nraise | refold_pos | upscale | bfgs_ndim | trust_radius_max | trust_radius_min | trust_radius_ini | w_1 | w_2

&CELL

cell_dynamics | press | wmass | cell_factor | press_conv_thr | cell_dofree

ATOMIC_SPECIES

X | Mass_X | PseudoPot_X

ATOMIC_POSITIONS

X | x | y | z | if_pos(1) | if_pos(2) | if_pos(3)

K_POINTS

nks | xk_x | xk_y | xk_z | wk | nk1 | nk2 | nk3 | sk1 | sk2 | sk3

CELL_PARAMETERS

v1 | v2 | v3

CONSTRAINTS

nconstr | constr_tol | constr_type | constr(1) | constr(2) | constr(3) | constr(4) | constr_target

OCCUPATIONS

f_inp1 | f_inp2

ATOMIC_FORCES

X | fx | fy | fz

INTRODUCTION

Input data format: { } = optional, [ ] = it depends, | = or

All quantities whose dimensions are not explicitly specified are in
RYDBERG ATOMIC UNITS. Charge is "number" charge (i.e. not multiplied
by e); potentials are in energy units (i.e. they are multiplied by e).

BEWARE: TABS, DOS <CR><LF> CHARACTERS ARE POTENTIAL SOURCES OF TROUBLE

Comment lines in namelists can be introduced by a "!", exactly as in
fortran code. Comments lines in cards can be introduced by
either a "!" or a "#" character in the first position of a line.
Do not start any line in cards with a "/" character.


Structure of the input data:
===============================================================================

&CONTROL
  ...
/

&SYSTEM
  ...
/

&ELECTRONS
  ...
/

[ &IONS
  ...
 / ]

[ &CELL
  ...
 / ]

ATOMIC_SPECIES
 X  Mass_X  PseudoPot_X
 Y  Mass_Y  PseudoPot_Y
 Z  Mass_Z  PseudoPot_Z

ATOMIC_POSITIONS { alat | bohr | crystal | angstrom | crystal_sg }
  X 0.0  0.0  0.0  {if_pos(1) if_pos(2) if_pos(3)}
  Y 0.5  0.0  0.0
  Z O.0  0.2  0.2

K_POINTS { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
if (gamma)
   nothing to read
if (automatic)
   nk1, nk2, nk3, k1, k2, k3
if (not automatic)
   nks
   xk_x, xk_y, xk_z,  wk

[ CELL_PARAMETERS { alat | bohr | angstrom }
   v1(1) v1(2) v1(3)
   v2(1) v2(2) v2(3)
   v3(1) v3(2) v3(3) ]

[ OCCUPATIONS
   f_inp1(1)  f_inp1(2)  f_inp1(3) ... f_inp1(10)
   f_inp1(11) f_inp1(12) ... f_inp1(nbnd)
 [ f_inp2(1)  f_inp2(2)  f_inp2(3) ... f_inp2(10)
   f_inp2(11) f_inp2(12) ... f_inp2(nbnd) ] ]

[ CONSTRAINTS
   nconstr  { constr_tol }
   constr_type(.)   constr(1,.)   constr(2,.) [ constr(3,.)   constr(4,.) ] { constr_target(.) } ]

[ ATOMIC_FORCES
   label_1 Fx(1) Fy(1) Fz(1)
   .....
   label_n Fx(n) Fy(n) Fz(n) ]
   

Namelist: &CONTROL

calculation CHARACTER
Default: 'scf'
A string describing the task to be performed. Options are:
            
'scf'
            
'nscf'
            
'bands'
            
'relax'
            
'md'
            
'vc-relax'
            
'vc-md'
            
(vc = variable-cell).
            
title CHARACTER
Default: ' '
reprinted on output.
         
verbosity CHARACTER
Default: 'low'
Currently two verbosity levels are implemented:
            
'high'
            
'low'
            
'debug' and 'medium' have the same effect as 'high';
'default' and 'minimal' as 'low'
            
restart_mode CHARACTER
Default: 'from_scratch'
 Available options are:
            
'from_scratch' :
From scratch. This is the normal way to perform a PWscf calculation
            
'restart' :
From previous interrupted run. Use this switch only if you want to
continue an interrupted calculation, not to start a new one, or to
perform non-scf calculations.  Works only if the calculation was
cleanly stopped using variable max_seconds, or by user request
with an "exit file" (i.e.: create a file "prefix".EXIT, in directory
"outdir"; see variables prefix, outdir).  Overrides startingwfc
and startingpot.
            
wf_collect LOGICAL
Default: .FALSE.
This flag controls the way wavefunctions are stored to disk :

.TRUE.  collect wavefunctions from all processors, store them
        into the output data directory "outdir"/"prefix".save,
        one wavefunction per k-point in subdirs K000001/,
        K000001/, etc.. Use this if you want wavefunctions
        to be readable on a different number of processors.

.FALSE. do not collect wavefunctions, leave them in temporary
        local files (one per processor). The resulting format
        will be readable only by jobs running on the same
        number of processors and pools. Requires less I/O
        than the previous case.

Note that this flag has no effect on reading, only on writing.
         
nstep INTEGER
Default: 1 if calculation == 'scf', 'nscf', 'bands'; 50 for the other cases
number of molecular-dynamics or structural optimization steps
performed in this run
         
iprint INTEGER
Default: write only at convergence
band energies are written every iprint iterations
         
tstress LOGICAL
Default: .false.
calculate stress. It is set to .TRUE. automatically if
calculation == 'vc-md' or 'vc-relax'
         
tprnfor LOGICAL
calculate forces. It is set to .TRUE. automatically if
calculation == 'relax','md','vc-md'
         
dt REAL
Default: 20.D0
time step for molecular dynamics, in Rydberg atomic units
(1 a.u.=4.8378 * 10^-17 s : beware, the CP code uses
 Hartree atomic units, half that much!!!)
         
outdir CHARACTER
Default: value of the ESPRESSO_TMPDIR environment variable if set; current directory ('./') otherwise
input, temporary, output files are found in this directory,
see also wfcdir
         
wfcdir CHARACTER
Default: same as outdir
This directory specifies where to store files generated by
each processor (*.wfc{N}, *.igk{N}, etc.). Useful for
machines without a parallel file system: set wfcdir to
a local file system, while outdir should be a parallel
or networkfile system, visible to all processors. Beware:
in order to restart from interrupted runs, or to perform
further calculations using the produced data files, you
may need to copy files to outdir. Works only for pw.x.
         
prefix CHARACTER
Default: 'pwscf'
prepended to input/output filenames:
prefix.wfc, prefix.rho, etc.
         
lkpoint_dir LOGICAL
Default: .true.
If .false. a subdirectory for each k_point is not opened
in the "prefix".save directory; Kohn-Sham eigenvalues are
stored instead in a single file for all k-points. Currently
doesn't work together with wf_collect
         
max_seconds REAL
Default: 1.D+7, or 150 days, i.e. no time limit
Jobs stops after max_seconds CPU time. Use this option
in conjunction with option restart_mode if you need to
split a job too long to complete into shorter jobs that
fit into your batch queues.
         
etot_conv_thr REAL
Default: 1.0D-4
Convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than etot_conv_thr
between two consecutive scf steps. Note that etot_conv_thr
is extensive, like the total energy.
See also forc_conv_thr - both criteria must be satisfied
         
forc_conv_thr REAL
Default: 1.0D-3
Convergence threshold on forces (a.u) for ionic minimization:
the convergence criterion is satisfied when all components of
all forces are smaller than forc_conv_thr.
See also etot_conv_thr - both criteria must be satisfied
         
disk_io CHARACTER
Default: see below
Specifies the amount of disk I/O activity:
            
'high' :
save all data to disk at each SCF step
            
'medium' :
save wavefunctions at each SCF step unless
there is a single k-point per process (in which
case the behavior is the same as 'low')
            
'low' :
store wfc in memory, save only at the end
            
'none' :
do not save anything, not even at the end
('scf', 'nscf', 'bands' calculations; some data
may be written anyway for other calculations)
            
Default is 'low' for the scf case, 'medium' otherwise.
Note that the needed RAM increases as disk I/O decreases!
It is no longer needed to specify 'high' in order to be able
to restart from an interrupted calculation (see restart_mode)
but you cannot restart in disk_io=='none'
            
pseudo_dir CHARACTER
Default: value of the $ESPRESSO_PSEUDO environment variable if set; '$HOME/espresso/pseudo/' otherwise
directory containing pseudopotential files
         
tefield LOGICAL
Default: .FALSE.
If .TRUE. a saw-like potential simulating an electric field
is added to the bare ionic potential. See variables edir,
eamp, emaxpos, eopreg for the form and size of
the added potential.
         
dipfield LOGICAL
Default: .FALSE.
If .TRUE. and tefield==.TRUE. a dipole correction is also
added to the bare ionic potential - implements the recipe
of L. Bengtsson, PRB 59, 12301 (1999). See variables edir,
emaxpos, eopreg for the form of the correction. Must
be used ONLY in a slab geometry, for surface calculations,
with the discontinuity FALLING IN THE EMPTY SPACE.
         
lelfield LOGICAL
Default: .FALSE.
If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
This is different from tefield == .true. !
         
nberrycyc INTEGER
Default: 1
In the case of a finite electric field  ( lelfield == .TRUE. )
it defines the number of iterations for converging the
wavefunctions in the electric field Hamiltonian, for each
external iteration on the charge density
         
lorbm LOGICAL
Default: .FALSE.
If .TRUE. perform orbital magnetization calculation.
If finite electric field is applied (lelfield==.true.)
only Kubo terms are computed
[for details see New J. Phys. 12, 053032 (2010)].
The type of calculation is 'nscf' and should be performed
on an automatically generated uniform grid of k points.
Works ONLY with norm-conserving pseudopotentials.
         
lberry LOGICAL
Default: .FALSE.
If .TRUE. perform a Berry phase calculation.
See the header of PW/src/bp_c_phase.f90 for documentation.
         
gdir INTEGER
For Berry phase calculation: direction of the k-point
strings in reciprocal space. Allowed values: 1, 2, 3
1=first, 2=second, 3=third reciprocal lattice vector
For calculations with finite electric fields
(lelfield==.true.) "gdir" is the direction of the field.
         
nppstr INTEGER
For Berry phase calculation: number of k-points to be
calculated along each symmetry-reduced string.
The same for calculation with finite electric fields
(lelfield==.true.).
         
lfcpopt LOGICAL
Default: .FALSE.
See: fcp_mu
If .TRUE. perform a constant bias potential (constant-mu) calculation
for a static system with ESM method. See the header of PW/src/fcp.f90
for documentation.

NB:
- The total energy displayed in 'prefix.out' includes the potentiostat
  contribution (-mu*N).
- calculation must be 'relax'.
- assume_isolated = 'esm' and esm_bc = 'bc2' or 'bc3' must be set
  in SYSTEM namelist.
         
monopole LOGICAL
Default: .FALSE.
See: zmon, realxz, block, block_1, block_2, block_height
In the case of charged cells (tot_charge .ne. 0) setting monopole = .TRUE.
represents the counter charge (i.e. -tot_charge) not by a homogenous
background charge but with a charged plate, which is placed at zmon
(see below). Details of the monopole potential can be found in
T. Brumme, M. Calandra, F. Mauri; PRB 89, 245406 (2014).
Note, that in systems which are not symmetric with respect to the plate,
one needs to enable the dipole correction! (dipfield=.true.).
Currently, symmetry can be used with monopole=.true. but carefully check
that no symmetry is included which maps z to -z even if in principle one
could still use them for symmetric systems (i.e. no dipole correction).
For nosym=.false. verbosity is set to 'high'.
         

Namelist: &SYSTEM

ibrav INTEGER
Status: REQUIRED
  Bravais-lattice index. If ibrav /= 0, specify EITHER
  [ celldm(1)-celldm(6) ] OR [ A, B, C, cosAB, cosAC, cosBC ]
  but NOT both. The lattice parameter "alat" is set to
  alat = celldm(1) (in a.u.) or alat = A (in Angstrom);
  see below for the other parameters.
  For ibrav=0 specify the lattice vectors in CELL_PARAMETERS,
  optionally the lattice parameter alat = celldm(1) (in a.u.)
  or = A (in Angstrom), or else it is taken from CELL_PARAMETERS

ibrav      structure                   celldm(2)-celldm(6)
                                     or: b,c,cosab,cosac,cosbc
  0          free
      crystal axis provided in input: see card CELL_PARAMETERS

  1          cubic P (sc)
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,1)

  2          cubic F (fcc)
      v1 = (a/2)(-1,0,1),  v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)

  3          cubic I (bcc)
      v1 = (a/2)(1,1,1),  v2 = (a/2)(-1,1,1),  v3 = (a/2)(-1,-1,1)

  4          Hexagonal and Trigonal P        celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(-1/2,sqrt(3)/2,0),  v3 = a(0,0,c/a)

  5          Trigonal R, 3fold axis c        celldm(4)=cos(alpha)
      The crystallographic vectors form a three-fold star around
      the z-axis, the primitive cell is a simple rhombohedron:
      v1 = a(tx,-ty,tz),   v2 = a(0,2ty,tz),   v3 = a(-tx,-ty,tz)
      where c=cos(alpha) is the cosine of the angle alpha between
      any pair of crystallographic vectors, tx, ty, tz are:
        tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)
 -5          Trigonal R, 3fold axis <111>    celldm(4)=cos(alpha)
      The crystallographic vectors form a three-fold star around
      <111>. Defining a' = a/sqrt(3) :
      v1 = a' (u,v,v),   v2 = a' (v,u,v),   v3 = a' (v,v,u)
      where u and v are defined as
        u = tz - 2*sqrt(2)*ty,  v = tz + sqrt(2)*ty
      and tx, ty, tz as for case ibrav=5
      Note: if you prefer x,y,z as axis in the cubic limit,
            set  u = tz + 2*sqrt(2)*ty,  v = tz - sqrt(2)*ty
            See also the note in Modules/latgen.f90

  6          Tetragonal P (st)               celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,c/a)

  7          Tetragonal I (bct)              celldm(3)=c/a
      v1=(a/2)(1,-1,c/a),  v2=(a/2)(1,1,c/a),  v3=(a/2)(-1,-1,c/a)

  8          Orthorhombic P                  celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a,0,0),  v2 = (0,b,0), v3 = (0,0,c)

  9          Orthorhombic base-centered(bco) celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2, b/2,0),  v2 = (-a/2,b/2,0),  v3 = (0,0,c)
 -9          as 9, alternate description
      v1 = (a/2,-b/2,0),  v2 = (a/2, b/2,0),  v3 = (0,0,c)

 10          Orthorhombic face-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2,0,c/2),  v2 = (a/2,b/2,0),  v3 = (0,b/2,c/2)

 11          Orthorhombic body-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1=(a/2,b/2,c/2),  v2=(-a/2,b/2,c/2),  v3=(-a/2,-b/2,c/2)

 12          Monoclinic P, unique axis c     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(4)=cos(ab)
      v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0),  v3 = (0,0,c)
      where gamma is the angle between axis a and b.
-12          Monoclinic P, unique axis b     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(5)=cos(ac)
      v1 = (a,0,0), v2 = (0,b,0), v3 = (c*cos(beta),0,c*sin(beta))
      where beta is the angle between axis a and c

 13          Monoclinic base-centered        celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(4)=cos(ab)
      v1 = (  a/2,         0,                -c/2),
      v2 = (b*cos(gamma), b*sin(gamma), 0),
      v3 = (  a/2,         0,                  c/2),
      where gamma is the angle between axis a and b

 14          Triclinic                       celldm(2)= b/a,
                                             celldm(3)= c/a,
                                             celldm(4)= cos(bc),
                                             celldm(5)= cos(ac),
                                             celldm(6)= cos(ab)
      v1 = (a, 0, 0),
      v2 = (b*cos(gamma), b*sin(gamma), 0)
      v3 = (c*cos(beta),  c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
           c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
                     - cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
      where alpha is the angle between axis b and c
             beta is the angle between axis a and c
            gamma is the angle between axis a and b
         

Either:

celldm(i), i=1,6 REAL
See: ibrav
Crystallographic constants - see the ibrav variable.
Specify either these OR A,B,C,cosAB,cosBC,cosAC NOT both.
Only needed values (depending on "ibrav") must be specified
alat = celldm(1) is the lattice parameter "a" (in BOHR)
If ibrav==0, only celldm(1) is used if present;
cell vectors are read from card CELL_PARAMETERS
            

Or:

A, B, C, cosAB, cosAC, cosBC REAL
See: ibrav
Traditional crystallographic constants:

  a,b,c in ANGSTROM
  cosAB = cosine of the angle between axis a and b (gamma)
  cosAC = cosine of the angle between axis a and c (beta)
  cosBC = cosine of the angle between axis b and c (alpha)

The axis are chosen according to the value of ibrav.
Specify either these OR celldm but NOT both.
Only needed values (depending on ibrav) must be specified.

The lattice parameter alat = A (in ANGSTROM ).

If ibrav == 0, only A is used if present, and
cell vectors are read from card CELL_PARAMETERS.
            
nat INTEGER
Status: REQUIRED
number of atoms in the unit cell (ALL atoms, except if
space_group is set, in which case, INEQUIVALENT atoms)
         
ntyp INTEGER
Status: REQUIRED
number of types of atoms in the unit cell
         
nbnd INTEGER
Default: for an insulator, nbnd = number of valence bands (nbnd = # of electrons /2);
for a metal, 20% more (minimum 4 more)
Number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
         
tot_charge REAL
Default: 0.0
Total charge of the system. Useful for simulations with charged cells.
By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.

In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.
         
tot_magnetization REAL
Default: -1 [unspecified]
Total majority spin charge - minority spin charge.
Used to impose a specific total electronic magnetization.
If unspecified then tot_magnetization variable is ignored and
the amount of electronic magnetization is determined during
the self-consistent cycle.
         
starting_magnetization(i), i=1,ntyp REAL
Starting spin polarization on atomic type 'i' in a spin
polarized calculation. Values range between -1 (all spins
down for the valence electrons of atom type 'i') to 1
(all spins up). Breaks the symmetry and provides a starting
point for self-consistency. The default value is zero, BUT a
value MUST be specified for AT LEAST one atomic type in spin
polarized calculations, unless you constrain the magnetization
(see tot_magnetization and constrained_magnetization).
Note that if you start from zero initial magnetization, you
will invariably end up in a nonmagnetic (zero magnetization)
state. If you want to start from an antiferromagnetic state,
you may need to define two different atomic species
corresponding to sublattices of the same atomic type.
starting_magnetization is ignored if you are performing a
non-scf calculation, if you are restarting from a previous
run, or restarting from an interrupted run.
If you fix the magnetization with tot_magnetization,
you should not specify starting_magnetization.
In the spin-orbit case starting with zero
starting_magnetization on all atoms imposes time reversal
symmetry. The magnetization is never calculated and
kept zero (the internal variable domag is .FALSE.).
         
ecutwfc REAL
Status: REQUIRED
kinetic energy cutoff (Ry) for wavefunctions
         
ecutrho REAL
Default: 4 * ecutwfc
Kinetic energy cutoff (Ry) for charge density and potential
For norm-conserving pseudopotential you should stick to the
default value, you can reduce it by a little but it will
introduce noise especially on forces and stress.
If there are ultrasoft PP, a larger value than the default is
often desirable (ecutrho = 8 to 12 times ecutwfc, typically).
PAW datasets can often be used at 4*ecutwfc, but it depends
on the shape of augmentation charge: testing is mandatory.
The use of gradient-corrected functional, especially in cells
with vacuum, or for pseudopotential without non-linear core
correction, usually requires an higher values of ecutrho
to be accurately converged.
         
ecutfock REAL
Default: ecutrho
Kinetic energy cutoff (Ry) for the exact exchange operator in
EXX type calculations. By default this is the same as ecutrho
but in some EXX calculations significant speed-up can be found
by reducing ecutfock, at the expense of some loss in accuracy.
Must be .gt. ecutwfc. Not implemented for stress calculation.
Use with care, especially in metals where it may give raise
to instabilities.
         
nr1, nr2, nr3 INTEGER
Three-dimensional FFT mesh (hard grid) for charge
density (and scf potential). If not specified
the grid is calculated based on the cutoff for
charge density (see also ecutrho)
Note: you must specify all three dimensions for this setting to
be used.
         
nr1s, nr2s, nr3s INTEGER
Three-dimensional mesh for wavefunction FFT and for the smooth
part of charge density ( smooth grid ).
Coincides with nr1, nr2, nr3 if ecutrho = 4 * ecutwfc ( default )
Note: you must specify all three dimensions for this setting to
be used.
         
nosym LOGICAL
Default: .FALSE.
if (.TRUE.) symmetry is not used, which means that:

- if a list of k points is provided in input, it is used
  "as is": symmetry-inequivalent k-points are not generated,
  and the charge density is not symmetrized;

- if a uniform (Monkhorst-Pack) k-point grid is provided in
  input, it is expanded to cover the entire Brillouin Zone,
  irrespective of the crystal symmetry.
  Time reversal symmetry is assumed so k and -k are considered
  as equivalent unless noinv=.true. is specified.

A careful usage of this option can be advantageous:
- in low-symmetry large cells, if you cannot afford a k-point
  grid with the correct symmetry
- in MD simulations
- in calculations for isolated atoms
         
nosym_evc LOGICAL
Default: .FALSE.
if (.TRUE.) symmetry is not used, and k points are
forced to have the symmetry of the Bravais lattice;
an automatically generated Monkhorst-Pack grid will contain
all points of the grid over the entire Brillouin Zone,
plus the points rotated by the symmetries of the Bravais
lattice which were not in the original grid. The same
applies if a k-point list is provided in input instead
of a Monkhorst-Pack grid. Time reversal symmetry is assumed
so k and -k are equivalent unless noinv=.true. is specified.
This option differs from nosym because it forces k-points
in all cases to have the full symmetry of the Bravais lattice
(not all uniform grids have such property!)
         
noinv LOGICAL
Default: .FALSE.
if (.TRUE.) disable the usage of k => -k symmetry
(time reversal) in k-point generation
         
no_t_rev LOGICAL
Default: .FALSE.
if (.TRUE.) disable the usage of magnetic symmetry operations
that consist in a rotation + time reversal.
         
force_symmorphic LOGICAL
Default: .FALSE.
if (.TRUE.) force the symmetry group to be symmorphic by disabling
symmetry operations having an associated fractionary translation
         
use_all_frac LOGICAL
Default: .FALSE.
if (.TRUE.) do not discard symmetry operations with an
associated fractionary translation that does not send the
real-space FFT grid into itself. These operations are
incompatible with real-space symmetrization but not with the
new G-space symmetrization. BEWARE: do not use for phonons
and for hybrid functionals! Both still use symmetrization
in real space.
         
occupations CHARACTER
 Available options are:
            
'smearing' :
gaussian smearing for metals;
see variables smearing and degauss
            
'tetrahedra' :
especially suited for calculation of DOS
(see P.E. Bloechl, PRB 49, 16223 (1994)).
Requires uniform grid of k-points,
automatically generated (see below).
Not suitable (because not variational) for
force/optimization/dynamics calculations.
            
'fixed' :
for insulators with a gap
            
'from_input' :
The occupation are read from input file,
card OCCUPATIONS. Option valid only for a
single k-point, requires nbnd to be set
in input. Occupations should be consistent
with the value of tot_charge.
            
one_atom_occupations LOGICAL
Default: .FALSE.
This flag is used for isolated atoms (nat=1) together with
occupations='from_input'. If it is .TRUE., the wavefunctions
are ordered as the atomic starting wavefunctions, independently
from their eigenvalue. The occupations indicate which atomic
states are filled.

The order of the states is written inside the UPF pseudopotential file.
In the scalar relativistic case:
S -> l=0, m=0
P -> l=1, z, x, y
D -> l=2, r^2-3z^2, xz, yz, xy, x^2-y^2

In the noncollinear magnetic case (with or without spin-orbit),
each group of states is doubled. For instance:
P -> l=1, z, x, y for spin up, l=1, z, x, y for spin down.
Up and down is relative to the direction of the starting
magnetization.

In the case with spin-orbit and time-reversal
(starting_magnetization=0.0) the atomic wavefunctions are
radial functions multiplied by spin-angle functions.
For instance:
P -> l=1, j=1/2, m_j=-1/2,1/2. l=1, j=3/2,
     m_j=-3/2, -1/2, 1/2, 3/2.

In the magnetic case with spin-orbit the atomic wavefunctions
can be forced to be spin-angle functions by setting
starting_spin_angle to .TRUE..
         
starting_spin_angle LOGICAL
Default: .FALSE.
In the spin-orbit case when domag=.TRUE., by default,
the starting wavefunctions are initialized as in scalar
relativistic noncollinear case without spin-orbit.

By setting starting_spin_angle=.TRUE. this behaviour can
be changed and the initial wavefunctions are radial
functions multiplied by spin-angle functions.

When domag=.FALSE. the initial wavefunctions are always
radial functions multiplied by spin-angle functions
independently from this flag.

When lspinorb is .FALSE. this flag is not used.
         
degauss REAL
Default: 0.D0 Ry
value of the gaussian spreading (Ry) for brillouin-zone
integration in metals.
         
smearing CHARACTER
Default: 'gaussian'
Available options are:
            
'gaussian', 'gauss' :
ordinary Gaussian spreading (Default)
            
'methfessel-paxton', 'm-p', 'mp' :
Methfessel-Paxton first-order spreading
(see PRB 40, 3616 (1989)).
            
'marzari-vanderbilt', 'cold', 'm-v', 'mv' :
Marzari-Vanderbilt cold smearing
(see PRL 82, 3296 (1999))
            
'fermi-dirac', 'f-d', 'fd' :
smearing with Fermi-Dirac function
            
nspin INTEGER
Default: 1
nspin = 1 :  non-polarized calculation (default)

nspin = 2 :  spin-polarized calculation, LSDA
             (magnetization along z axis)

nspin = 4 :  spin-polarized calculation, noncollinear
             (magnetization in generic direction)
             DO NOT specify nspin in this case;
             specify noncolin=.TRUE. instead
         
noncolin LOGICAL
Default: .false.
if .true. the program will perform a noncollinear calculation.
         
ecfixed REAL
Default: 0.0
See: q2sigma
qcutz REAL
Default: 0.0
See: q2sigma
q2sigma REAL
Default: 0.1
ecfixed, qcutz, q2sigma:  parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995)
         
input_dft CHARACTER
Default: read from pseudopotential files
Exchange-correlation functional: eg 'PBE', 'BLYP' etc
See Modules/funct.f90 for allowed values.
Overrides the value read from pseudopotential files.
Use with care and if you know what you are doing!
         
exx_fraction REAL
Default: it depends on the specified functional
Fraction of EXX for hybrid functional calculations. In the case of
input_dft='PBE0', the default value is 0.25, while for input_dft='B3LYP'
the exx_fraction default value is 0.20.
         
screening_parameter REAL
Default: 0.106
screening_parameter for HSE like hybrid functionals.
See J. Chem. Phys. 118, 8207 (2003)
and J. Chem. Phys. 124, 219906 (2006) for more informations.
         
exxdiv_treatment CHARACTER
Default: 'gygi-baldereschi'
Specific for EXX. It selects the kind of approach to be used
for treating the Coulomb potential divergencies at small q vectors.
            
'gygi-baldereschi' :
 appropriate for cubic and quasi-cubic supercells
            
'vcut_spherical' :
 appropriate for cubic and quasi-cubic supercells
            
'vcut_ws' :
 appropriate for strongly anisotropic supercells, see also ecutvcut.
            
'none' :
 sets Coulomb potential at G,q=0 to 0.0 (required for GAU-PBE)
            
x_gamma_extrapolation LOGICAL
Default: .true.
Specific for EXX. If .true., extrapolate the G=0 term of the
potential (see README in examples/EXX_example for more)
Set this to .false. for GAU-PBE.
         
ecutvcut REAL
Default: 0.0 Ry
See: exxdiv_treatment
Reciprocal space cutoff for correcting Coulomb potential
divergencies at small q vectors.
         
nqx1, nqx2, nqx3 INTEGER
Three-dimensional mesh for q (k1-k2) sampling of
the Fock operator (EXX). Can be smaller than
the number of k-points.

Currently this defaults to the size of the k-point mesh used.
In QE =< 5.0.2 it defaulted to nqx1=nqx2=nqx3=1.
         
lda_plus_u LOGICAL
Default: .FALSE.
Status: DFT+U (formerly known as LDA+U) currently works only for a few selected elements. Modify Modules/set_hubbard_l.f90 and PW/src/tabd.f90 if you plan to use DFT+U with an element that is not configured there.
Specify lda_plus_u = .TRUE. to enable DFT+U calculations
See: Anisimov, Zaanen, and Andersen, PRB 44, 943 (1991);
     Anisimov et al., PRB 48, 16929 (1993);
     Liechtenstein, Anisimov, and Zaanen, PRB 52, R5467 (1994).
You must specify, for each species with a U term, the value of
U and (optionally) alpha, J of the Hubbard model (all in eV):
see lda_plus_u_kind, Hubbard_U, Hubbard_alpha, Hubbard_J
         
lda_plus_u_kind INTEGER
Default: 0
Specifies the type of DFT+U calculation:

   0   simplified version of Cococcioni and de Gironcoli,
       PRB 71, 035105 (2005), using Hubbard_U

   1   rotationally invariant scheme of Liechtenstein et al.,
       using Hubbard_U and Hubbard_J
         
Hubbard_U(i), i=1,ntyp REAL
Default: 0.D0 for all species
Hubbard_U(i): U parameter (eV) for species i, DFT+U calculation
         
Hubbard_J0(i), i=1,ntype REAL
Default: 0.D0 for all species
Hubbard_J0(i): J0 parameter (eV) for species i, DFT+U+J calculation,
see PRB 84, 115108 (2011) for details.
         
Hubbard_alpha(i), i=1,ntyp REAL
Default: 0.D0 for all species
Hubbard_alpha(i) is the perturbation (on atom i, in eV)
used to compute U with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 35105 (2005)
(only for lda_plus_u_kind=0)
         
Hubbard_beta(i), i=1,ntyp REAL
Default: 0.D0 for all species
Hubbard_beta(i) is the perturbation (on atom i, in eV)
used to compute J0 with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 35105 (2005)
(only for lda_plus_u_kind=0). See also
PRB 84, 115108 (2011).
         
Hubbard_J(i,ityp)
Default: 0.D0 for all species
Hubbard_J(i,ityp): J parameters (eV) for species ityp,
used in DFT+U calculations (only for lda_plus_u_kind=1)
For p orbitals:  J = Hubbard_J(1,ityp);
For d orbitals:  J = Hubbard_J(1,ityp), B = Hubbard_J(2,ityp);
For f orbitals:  J = Hubbard_J(1,ityp), E2 = Hubbard_J(2,ityp),
                 E3= Hubbard_J(3,ityp).
If B or E2 or E3 are not specified or set to 0 they will be
calculated from J using atomic ratios.
         
starting_ns_eigenvalue(m,ispin,I) REAL
Default: -1.d0 that means NOT SET
In the first iteration of an DFT+U run it overwrites
the m-th eigenvalue of the ns occupation matrix for the
ispin component of atomic species I. Leave unchanged
eigenvalues that are not set. This is useful to suggest
the desired orbital occupations when the default choice
takes another path.
         
U_projection_type CHARACTER
Default: 'atomic'
Only active when lda_plus_U is .true., specifies the type
of projector on localized orbital to be used in the DFT+U
scheme.

Currently available choices:
            
'atomic' :
 use atomic wfc's (as they are) to build the projector
            
'ortho-atomic' :
 use Lowdin orthogonalized atomic wfc's
            
'norm-atomic' :
Lowdin normalization of atomic wfc. Keep in mind:
atomic wfc are not orthogonalized in this case.
This is a "quick and dirty" trick to be used when
atomic wfc from the pseudopotential are not
normalized (and thus produce occupation whose
value exceeds unity). If orthogonalized wfc are
not needed always try 'atomic' first.
            
'file' :
use the information from file "prefix".atwfc that must
have been generated previously, for instance by pmw.x
(see PP/src/poormanwannier.f90 for details).
            
'pseudo' :
use the pseudopotential projectors. The charge density
outside the atomic core radii is excluded.
N.B.: for atoms with +U, a pseudopotential with the
all-electron atomic wavefunctions is required (i.e.,
as generated by ld1.x with lsave_wfc flag).
            
NB: forces and stress currently implemented only for the
'atomic' and 'pseudo' choice.
            
edir INTEGER
The direction of the electric field or dipole correction is
parallel to the bg(:,edir) reciprocal lattice vector, so the
potential is constant in planes defined by FFT grid points;
edir = 1, 2 or 3. Used only if tefield is .TRUE.
         
emaxpos REAL
Default: 0.5D0
Position of the maximum of the saw-like potential along crystal
axis edir, within the  unit cell (see below), 0 < emaxpos < 1
Used only if tefield is .TRUE.
         
eopreg REAL
Default: 0.1D0
Zone in the unit cell where the saw-like potential decreases.
( see below, 0 < eopreg < 1 ). Used only if tefield is .TRUE.
         
eamp REAL
Default: 0.001 a.u.
Amplitude of the electric field, in ***Hartree*** a.u.;
1 a.u. = 51.4220632*10^10 V/m. Used only if tefield==.TRUE.
The saw-like potential increases with slope eamp in the
region from (emaxpos+eopreg-1) to (emaxpos), then decreases
to 0 until (emaxpos+eopreg), in units of the crystal
vector edir. Important: the change of slope of this
potential must be located in the empty region, or else
unphysical forces will result.
         
angle1(i), i=1,ntyp REAL
The angle expressed in degrees between the initial
magnetization and the z-axis. For noncollinear calculations
only; index i runs over the atom types.
         
angle2(i), i=1,ntyp REAL
The angle expressed in degrees between the projection
of the initial magnetization on x-y plane and the x-axis.
For noncollinear calculations only.
         
constrained_magnetization CHARACTER
Default: 'none'
See: lambda, fixed_magnetization
Used to perform constrained calculations in magnetic systems.
Currently available choices:
            
'none' :
no constraint
            
'total' :
total magnetization is constrained by
adding a penalty functional to the total energy:

LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i) )**2

where the sum over i runs over the three components of
the magnetization. Lambda is a real number (see below).
Noncolinear case only. Use tot_magnetization for LSDA
            
'atomic' :
atomic magnetization are constrained to the defined
starting magnetization adding a penalty:

LAMBDA * SUM_{i,itype} ( magnetic_moment(i,itype) - mcons(i,itype) )**2

where i runs over the cartesian components (or just z
in the collinear case) and itype over the types (1-ntype).
mcons(:,:) array is defined from starting_magnetization,
(and angle1, angle2 in the non-collinear case). lambda is
a real number
            
'total direction' :
the angle theta of the total magnetization
with the z axis (theta = fixed_magnetization(3))
is constrained:

LAMBDA * ( arccos(magnetization(3)/mag_tot) - theta )**2

where mag_tot is the modulus of the total magnetization.
            
'atomic direction' :
not all the components of the atomic
magnetic moment are constrained but only the cosine
of angle1, and the penalty functional is:

LAMBDA * SUM_{itype} ( mag_mom(3,itype)/mag_mom_tot - cos(angle1(ityp)) )**2
            
N.B.: symmetrization may prevent to reach the desired orientation
of the magnetization. Try not to start with very highly symmetric
configurations or use the nosym flag (only as a last remedy)
            
fixed_magnetization(i), i=1,3 REAL
Default: 0.d0
See: constrained_magnetization
total magnetization vector (x,y,z components) to be kept
fixed when constrained_magnetization=='total'
         
lambda REAL
Default: 1.d0
See: constrained_magnetization
parameter used for constrained_magnetization calculations
N.B.: if the scf calculation does not converge, try to reduce lambda
      to obtain convergence, then restart the run with a larger lambda
         
report INTEGER
Default: 100
Number of iterations after which the program
writes all the atomic magnetic moments.
         
lspinorb LOGICAL
if .TRUE. the noncollinear code can use a pseudopotential with
spin-orbit.
         
assume_isolated CHARACTER
Default: 'none'
Used to perform calculation assuming the system to be
isolated (a molecule or a cluster in a 3D supercell).

Currently available choices:
            
'none' :
(default): regular periodic calculation w/o any correction.
            
'makov-payne', 'm-p', 'mp' :
the Makov-Payne correction to the
total energy is computed. An estimate of the vacuum
level is also calculated so that eigenvalues can be
properly aligned. ONLY FOR CUBIC SYSTEMS (ibrav=1,2,3).
Theory: G.Makov, and M.C.Payne,
     "Periodic boundary conditions in ab initio
     calculations" , PRB 51, 4014 (1995).
            
'martyna-tuckerman', 'm-t', 'mt' :
Martyna-Tuckerman correction
to both total energy and scf potential. Adapted from:
G.J. Martyna, and M.E. Tuckerman,
"A reciprocal space based method for treating long
range interactions in ab-initio and force-field-based
calculation in clusters", J.Chem.Phys. 110, 2810 (1999).
            
'esm' :
Effective Screening Medium Method.
For polarized or charged slab calculation, embeds
the simulation cell within an effective semi-
infinite medium in the perpendicular direction
(along z). Embedding regions can be vacuum or
semi-infinite metal electrodes (use 'esm_bc' to
choose boundary conditions). If between two
electrodes, an optional electric field
('esm_efield') may be applied. Method described in
M. Otani and O. Sugino, "First-principles calculations
of charged surfaces and interfaces: A plane-wave
nonrepeated slab approach", PRB 73, 115407 (2006).

NB:
   - Two dimensional (xy plane) average charge density
     and electrostatic potentials are printed out to
     'prefix.esm1'.

   - Requires cell with a_3 lattice vector along z,
     normal to the xy plane, with the slab centered
     around z=0. Also requires symmetry checking to be
     disabled along z, either by setting nosym = .TRUE.
     or by very slight displacement (i.e., 5e-4 a.u.)
     of the slab along z.

See esm_bc, esm_efield, esm_w, esm_nfit.
            
esm_bc CHARACTER
Default: 'pbc'
See: assume_isolated
If assume_isolated = 'esm', determines the boundary
conditions used for either side of the slab.

Currently available choices:
            
'pbc' :
 (default): regular periodic calculation (no ESM).
            
'bc1' :
 Vacuum-slab-vacuum (open boundary conditions).
            
'bc2' :
Metal-slab-metal (dual electrode configuration).
See also esm_efield.
            
'bc3' :
 Vacuum-slab-metal
            
esm_w REAL
Default: 0.d0
See: assume_isolated
If assume_isolated = 'esm', determines the position offset
[in a.u.] of the start of the effective screening region,
measured relative to the cell edge. (ESM region begins at
z = +/- [L_z/2 + esm_w] ).
         
esm_efield REAL
Default: 0.d0
See: assume_isolated
If assume_isolated = 'esm' and esm_bc = 'bc2', gives the
magnitude of the electric field [Ry/a.u.] to be applied
between semi-infinite ESM electrodes.
         
esm_nfit INTEGER
Default: 4
See: assume_isolated
If assume_isolated = 'esm', gives the number of z-grid points
for the polynomial fit along the cell edge.
         
fcp_mu REAL
Default: 0.d0
See: lfcpopt
If lfcpopt = .TRUE., gives the target Fermi energy [Ry]. One can start
with appropriate total charge of the system by giving 'tot_charge'.
         
vdw_corr CHARACTER
Default: 'none'
See: london_s6, london_rcut, london_c6, london_rvdw, ts_vdw_econv_thr, ts_vdw_isolated, xdm_a1, xdm_a2
Type of Van der Waals correction. Allowed values:
            
'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d' :
Semiempirical Grimme's DFT-D2.
Optional variables: london_s6, london_rcut, london_c6, london_rvdw,
S. Grimme, J. Comp. Chem. 27, 1787 (2006),
V. Barone et al., J. Comp. Chem. 30, 934 (2009).
            
'TS', 'ts', 'ts-vdw', 'ts-vdW', 'tkatchenko-scheffler' :
Tkatchenko-Scheffler dispersion corrections with first-principle derived
C6 coefficients (implemented in CP only).
Optional variables: ts_vdw_econv_thr, ts_vdw_isolated
See A. Tkatchenko and M. Scheffler, PRL 102, 073005 (2009).
            
'XDM', 'xdm' :
Exchange-hole dipole-moment model. Optional variables: xdm_a1, xdm_a2
A. D. Becke and E. R. Johnson, J. Chem. Phys. 127, 154108 (2007)
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 136, 174109 (2012)
            
 Note that non-local functionals (eg vdw-DF) are NOT specified here but in input_dft
            
london LOGICAL
Default: .FALSE.
Status: OBSOLESCENT, same as vdw_corr='DFT-D'
london_s6 REAL
Default: 0.75
global scaling parameter for DFT-D. Default is good for PBE.
         
london_c6(i), i=1,ntyp REAL
Default: standard Grimme-D2 values
atomic C6 coefficient of each atom type

( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006) are used;
  see file Modules/mm_dispersion.f90 )
         
london_rvdw(i), i=1,ntyp REAL
Default: standard Grimme-D2 values
atomic vdw radii of each atom type

( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006) are used;
  see file Modules/mm_dispersion.f90 )
         
london_rcut REAL
Default: 200
cutoff radius (a.u.) for dispersion interactions
         
ts_vdw_econv_thr REAL
Default: 1.D-6
Optional: controls the convergence of the vdW energy (and forces). The default value
is a safe choice, likely too safe, but you do not gain much in increasing it
         
ts_vdw_isolated LOGICAL
Default: .FALSE.
Optional: set it to .TRUE. when computing the Tkatchenko-Scheffler vdW energy
for an isolated (non-periodic) system.
         
xdm LOGICAL
Default: .FALSE.
Status: OBSOLESCENT, same as vdw_corr='xdm'
xdm_a1 REAL
Default: 0.6836
Damping function parameter a1 (adimensional). This value should change
with the exchange-correlation functional. The default corresponds to
PW86PBE.
For other functionals, see:
   http://schooner.chem.dal.ca/wiki/XDM
   A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013)
         
xdm_a2 REAL
Default: 1.5045
Damping function parameter a2 (angstrom). This value should change
with the exchange-correlation functional. The default corresponds to
PW86PBE.
For other functionals, see:
   http://schooner.chem.dal.ca/wiki/XDM
   A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013)
         
space_group INTEGER
Default: 0
The number of the space group of the crystal, as given
in the International Tables of Crystallography A (ITA).
This allows to give in input only the inequivalent atomic
positions. The positions of all the symmetry equivalent atoms
are calculated by the code. Used only when the atomic positions
are of type crystal_sg.
         
uniqueb LOGICAL
Default: .FALSE.
Used only for monoclinic lattices. If .TRUE. the b
unique ibrav (-12 or -13) are used, and symmetry
equivalent positions are chosen assuming that the
two fold axis or the mirror normal is parallel to the
b axis. If .FALSE. it is parallel to the c axis.
         
origin_choice INTEGER
Default: 1
Used only for space groups that in the ITA allow
the use of two different origins. origin_choice=1,
means the first origin, while origin_choice=2 is the
second origin.
         
rhombohedral LOGICAL
Default: .TRUE.
Used only for rhombohedral space groups.
When .TRUE. the coordinates of the inequivalent atoms are
given with respect to the rhombohedral axes, when .FALSE.
the coordinates of the inequivalent atoms are given with
respect to the hexagonal axes. They are converted internally
to the rhombohedral axes and ibrav=5 is used in both cases.
         

below variables are used only if monopole = .TRUE.

zmon REAL
Default: 0.5
used only if monopole = .TRUE.
Specifies the position of the charged plate which represents
the counter charge in doped systems (tot_charge .ne. 0).
In units of the unit cell length in z direction, zmon in ]0,1[
Details of the monopole potential can be found in
T. Brumme, M. Calandra, F. Mauri; PRB 89, 245406 (2014).
            
realxz LOGICAL
Default: .FALSE.
used only if monopole = .TRUE.
Allows the relaxation of the system towards the charged plate.
Use carefully and utilize either a layer of fixed atoms or a
potential barrier (block=.TRUE.) to avoid the atoms moving to
the position of the plate or the dipole of the dipole
correction (dipfield=.TRUE.).
            
block LOGICAL
Default: .FALSE.
used only if monopole = .TRUE.
Adds a potential barrier to the total potential seen by the
electrons to mimic a dielectric in field effect configuration
and/or to avoid electrons spilling into the vacuum region for
electron doping. Potential barrier is from block_1 to block_2 and
has a height of block_height.
If dipfield = .TRUE. then eopreg is used for a smooth increase and
decrease of the potential barrier.
            
block_1 REAL
Default: 0.45
used only if monopole = .TRUE. and block = .TRUE.
lower beginning of the potential barrier, in units of the
unit cell size along z, block_1 in ]0,1[
            
block_2 REAL
Default: 0.55
used only if monopole = .TRUE. and block = .TRUE.
upper beginning of the potential barrier, in units of the
unit cell size along z, block_2 in ]0,1[
            
block_height REAL
Default: 0.1
used only if monopole = .TRUE. and block = .TRUE.
Height of the potential barrier in Rydberg.
            

Namelist: &ELECTRONS

electron_maxstep INTEGER
Default: 100
maximum number of iterations in a scf step
         
scf_must_converge LOGICAL
Default: .TRUE.
If .false. do not stop molecular dynamics or ionic relaxation
when electron_maxstep is reached. Use with care.
         
conv_thr REAL
Default: 1.D-6
Convergence threshold for selfconsistency:
   estimated energy error < conv_thr
(note that conv_thr is extensive, like the total energy).

For non-self-consistent calculations, conv_thr is used
to set the default value of the threshold (ethr) for
iterative diagonalizazion: see diago_thr_init
         
adaptive_thr LOGICAL
Default: .FALSE
If .TRUE. this turns on the use of an adaptive conv_thr for
the inner scf loops when using EXX.
         
conv_thr_init REAL
Default: 1.D-3
When adaptive_thr = .TRUE. this is the convergence threshold
used for the first scf cycle.
         
conv_thr_multi REAL
Default: 1.D-1
When adaptive_thr = .TRUE. the convergence threshold for
each scf cycle is given by:
max( conv_thr, conv_thr_multi * dexx )
         
mixing_mode CHARACTER
Default: 'plain'
 Available options are:
            
'plain' :
 charge density Broyden mixing
            
'TF' :
as above, with simple Thomas-Fermi screening
(for highly homogeneous systems)
            
'local-TF' :
as above, with local-density-dependent TF screening
(for highly inhomogeneous systems)
            
mixing_beta REAL
Default: 0.7D0
mixing factor for self-consistency
         
mixing_ndim INTEGER
Default: 8
number of iterations used in mixing scheme.
If you are tight with memory, you may reduce it to 4 or so.
         
mixing_fixed_ns INTEGER
Default: 0
For DFT+U : number of iterations with fixed ns ( ns is the
atomic density appearing in the Hubbard term ).
         
diagonalization CHARACTER
Default: 'david'
 Available options are:
            
'david' :
Davidson iterative diagonalization with overlap matrix
(default). Fast, may in some rare cases fail.
            
'cg' :
Conjugate-gradient-like band-by-band diagonalization.
Typically slower than 'david' but it uses less memory
and is more robust (it seldom fails).
            
'cg-serial', 'david-serial' :
OBSOLETE, use -ndiag 1 instead.
The subspace diagonalization in Davidson is performed
by a fully distributed-memory parallel algorithm on
4 or more processors, by default. The allocated memory
scales down with the number of procs. Procs involved
in diagonalization can be changed with command-line
option -ndiag N. On multicore CPUs it is often
convenient to let just one core per CPU to work
on linear algebra.
            
ortho_para INTEGER
Default: 0
Status: OBSOLETE: use command-line option "-ndiag XX" instead
diago_thr_init REAL
Convergence threshold (ethr) for iterative diagonalization
(the check is on eigenvalue convergence).

For scf calculations: default is 1.D-2 if starting from a
superposition of atomic orbitals; 1.D-5 if starting from a
charge density. During self consistency the threshold
is automatically reduced (but never below 1.D-13) when
approaching convergence.

For non-scf calculations: default is (conv_thr/N elec)/10.
         
diago_cg_maxiter INTEGER
For conjugate gradient diagonalization:  max number of iterations
         
diago_david_ndim INTEGER
Default: 4
For Davidson diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
A larger value may yield a somewhat faster algorithm
but uses more memory. The opposite holds for smaller values.
Try diago_david_ndim=2 if you are tight on memory or if
your job is large: the speed penalty is often negligible
         
diago_full_acc LOGICAL
Default: .FALSE.
If .TRUE. all the empty states are diagonalized at the same level
of accuracy of the occupied ones. Otherwise the empty states are
diagonalized using a larger threshold (this should not affect
total energy, forces, and other ground-state properties).
         
efield REAL
Default: 0.D0
Amplitude of the finite electric field (in Ry a.u.;
1 a.u. = 36.3609*10^10 V/m). Used only if lelfield==.TRUE.
and if k-points (K_POINTS card) are not automatic.
         
efield_cart(i), i=1,3 REAL
Default: (0.D0, 0.D0, 0.D0)
Finite electric field (in Ry a.u.=36.3609*10^10 V/m) in
cartesian axis. Used only if lelfield==.TRUE. and if
k-points (K_POINTS card) are automatic.
         
efield_phase CHARACTER
Default: 'none'
 Available options are:
            
'read' :
set the zero of the electronic polarization (with lelfield==.true..)
to the result of a previous calculation
            
'write' :
write on disk data on electronic polarization to be read in another
calculation
            
'none' :
none of the above points
            
startingpot CHARACTER
 Available options are:
            
'atomic' :
starting potential from atomic charge superposition
(default for scf, *relax, *md)
            
'file' :
start from existing "charge-density.xml" file in the
directory specified by variables prefix and outdir
For nscf and bands calculation this is the default
and the only sensible possibility.
            
startingwfc CHARACTER
Default: 'atomic+random'
 Available options are:
            
'atomic' :
Start from superposition of atomic orbitals.
If not enough atomic orbitals are available,
fill with random numbers the remaining wfcs
The scf typically starts better with this option,
but in some high-symmetry cases one can "loose"
valence states, ending up in the wrong ground state.
            
'atomic+random' :
As above, plus a superimposed "randomization"
of atomic orbitals. Prevents the "loss" of states
mentioned above.
            
'random' :
Start from random wfcs. Slower start of scf but safe.
It may also reduce memory usage in conjunction with
diagonalization='cg'.
            
'file' :
Start from an existing wavefunction file in the
directory specified by variables prefix and outdir.
            
tqr LOGICAL
Default: .FALSE.
If .true., use the real-space algorithm for augmentation
charges in ultrasoft pseudopotentials.
Must faster execution of ultrasoft-related calculations,
but numerically less accurate than the default algorithm.
Use with care and after testing!
         

Namelist: &IONS

input this namelist only if calculation == 'relax', 'md', 'vc-relax', or 'vc-md'

ion_dynamics CHARACTER
Specify the type of ionic dynamics.

For different type of calculation different possibilities are
allowed and different default values apply:

CASE ( calculation == 'relax' )
            
'bfgs' :
(default)  use BFGS quasi-newton algorithm,
based on the trust radius procedure,
for structural relaxation
            
'damp' :
use damped (quick-min Verlet)
dynamics for structural relaxation
Can be used for constrained
optimisation: see CONSTRAINTS card
            
CASE ( calculation == 'md' )
            
'verlet' :
(default)  use Verlet algorithm to integrate
Newton's equation. For constrained
dynamics, see CONSTRAINTS card
            
'langevin' :
ion dynamics is over-damped Langevin
            
'langevin-smc' :
over-damped Langevin with Smart Monte Carlo:
see R.J. Rossky, JCP, 69, 4628(1978)
            
CASE ( calculation == 'vc-relax' )
            
'bfgs' :
(default)  use BFGS quasi-newton algorithm;
cell_dynamics must be 'bfgs' too
            
'damp' :
use damped (Beeman) dynamics for
structural relaxation
            
CASE ( calculation == 'vc-md' )
            
'beeman' :
(default)  use Beeman algorithm to integrate
Newton's equation
            
ion_positions CHARACTER
Default: 'default'
 Available options are:
            
'default' :
if restarting, use atomic positions read from the
restart file; in all other cases, use atomic
positions from standard input.
            
'from_input' :
restart the simulation with atomic positions read
from standard input, even if restarting.
            
pot_extrapolation CHARACTER
Default: 'atomic'
Used to extrapolate the potential from preceding ionic steps.
            
'none' :
 no extrapolation
            
'atomic' :
extrapolate the potential as if it was a sum of
atomic-like orbitals
            
'first_order' :
extrapolate the potential with first-order
formula
            
'second_order' :
as above, with second order formula
            
Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
            
wfc_extrapolation CHARACTER
Default: 'none'
Used to extrapolate the wavefunctions from preceding ionic steps.
            
'none' :
 no extrapolation
            
'first_order' :
extrapolate the wave-functions with first-order formula.
            
'second_order' :
as above, with second order formula.
            
Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
            
remove_rigid_rot LOGICAL
Default: .FALSE.
This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allows for the use of smaller supercells.

BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
         

variables used for molecular dynamics

ion_temperature CHARACTER
Default: 'not_controlled'
 Available options are:
               
'rescaling' :
control ionic temperature via velocity rescaling
(first method) see parameters tempw, tolp, and
nraise (for VC-MD only). This rescaling method
is the only one currently implemented in VC-MD
               
'rescale-v' :
control ionic temperature via velocity rescaling
(second method) see parameters tempw and nraise
               
'rescale-T' :
control ionic temperature via velocity rescaling
(third method) see parameter delta_t
               
'reduce-T' :
reduce ionic temperature every nraise steps
by the (negative) value delta_t
               
'berendsen' :
control ionic temperature using "soft" velocity
rescaling - see parameters tempw and nraise
               
'andersen' :
control ionic temperature using Andersen thermostat
see parameters tempw and nraise
               
'initial' :
initialize ion velocities to temperature tempw
and leave uncontrolled further on
               
'not_controlled' :
(default) ionic temperature is not controlled
               
tempw REAL
Default: 300.D0
Starting temperature (Kelvin) in MD runs
target temperature for most thermostats.
            
tolp REAL
Default: 100.D0
Tolerance for velocity rescaling. Velocities are rescaled if
the run-averaged and target temperature differ more than tolp.
            
delta_t REAL
Default: 1.D0
if ion_temperature == 'rescale-T' :
       at each step the instantaneous temperature is multiplied
       by delta_t; this is done rescaling all the velocities.

if ion_temperature == 'reduce-T' :
       every 'nraise' steps the instantaneous temperature is
       reduced by -delta_t (i.e. delta_t < 0 is added to T)

The instantaneous temperature is calculated at the end of
every ionic move and BEFORE rescaling. This is the temperature
reported in the main output.

For delta_t < 0, the actual average rate of heating or cooling
should be roughly C*delta_t/(nraise*dt) (C=1 for an
ideal gas, C=0.5 for a harmonic solid, theorem of energy
equipartition between all quadratic degrees of freedom).
            
nraise INTEGER
Default: 1
if ion_temperature == 'reduce-T' :
       every nraise steps the instantaneous temperature is
       reduced by -delta_t (i.e. delta_t is added to the temperature)

if ion_temperature == 'rescale-v' :
       every nraise steps the average temperature, computed from
       the last nraise steps, is rescaled to tempw

if ion_temperature == 'rescaling' and calculation == 'vc-md' :
       every nraise steps the instantaneous temperature
       is rescaled to tempw

if ion_temperature == 'berendsen' :
       the "rise time" parameter is given in units of the time step:
       tau = nraise*dt, so dt/tau = 1/nraise

if ion_temperature == 'andersen' :
       the "collision frequency" parameter is given as nu=1/tau
       defined above, so nu*dt = 1/nraise
            
refold_pos LOGICAL
Default: .FALSE.
This keyword applies only in the case of molecular dynamics or
damped dynamics. If true the ions are refolded at each step into
the supercell.
            

keywords used only in BFGS calculations

upscale REAL
Default: 100.D0
Max reduction factor for conv_thr during structural optimization
conv_thr is automatically reduced when the relaxation
approaches convergence so that forces are still accurate,
but conv_thr will not be reduced to less that conv_thr / upscale.
            
bfgs_ndim INTEGER
Default: 1
Number of old forces and displacements vectors used in the
PULAY mixing of the residual vectors obtained on the basis
of the inverse hessian matrix given by the BFGS algorithm.
When bfgs_ndim = 1, the standard quasi-Newton BFGS method is
used.
(bfgs only)
            
trust_radius_max REAL
Default: 0.8D0
Maximum ionic displacement in the structural relaxation.
(bfgs only)
            
trust_radius_min REAL
Default: 1.D-3
Minimum ionic displacement in the structural relaxation
BFGS is reset when trust_radius < trust_radius_min.
(bfgs only)
            
trust_radius_ini REAL
Default: 0.5D0
Initial ionic displacement in the structural relaxation.
(bfgs only)
            
w_1 REAL
Default: 0.01D0
See: w_2
w_2 REAL
Default: 0.5D0
Parameters used in line search based on the Wolfe conditions.
(bfgs only)
            

Namelist: &CELL

input this namelist only if calculation == 'vc-relax' or 'vc-md'

cell_dynamics CHARACTER
Specify the type of dynamics for the cell.
For different type of calculation different possibilities
are allowed and different default values apply:

CASE ( calculation == 'vc-relax' )
            
'none' :
 no dynamics
            
'sd' :
 steepest descent ( not implemented )
            
'damp-pr' :
damped (Beeman) dynamics of the Parrinello-Rahman extended lagrangian
            
'damp-w' :
damped (Beeman) dynamics of the new Wentzcovitch extended lagrangian
            
'bfgs' :
BFGS quasi-newton algorithm (default)
ion_dynamics must be 'bfgs' too
            
CASE ( calculation == 'vc-md' )
            
'none' :
 no dynamics
            
'pr' :
(Beeman) molecular dynamics of the Parrinello-Rahman extended lagrangian
            
'w' :
(Beeman) molecular dynamics of the new Wentzcovitch extended lagrangian
            
press REAL
Default: 0.D0
Target pressure [KBar] in a variable-cell md or relaxation run.
         
wmass REAL
Default: 0.75*Tot_Mass/pi**2 for Parrinello-Rahman MD; 0.75*Tot_Mass/pi**2/Omega**(2/3) for Wentzcovitch MD
Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
         
cell_factor REAL
Default: 1.2D0
Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
         
press_conv_thr REAL
Default: 0.5D0 Kbar
Convergence threshold on the pressure for variable cell
relaxation ('vc-relax' : note that the other convergence
            thresholds for ionic relaxation apply as well).
         
cell_dofree CHARACTER
Default: 'all'
Select which of the cell parameters should be moved:
            
'all' :
 all axis and angles are moved
            
'x' :
 only the x component of axis 1 (v1_x) is moved
            
'y' :
 only the y component of axis 2 (v2_y) is moved
            
'z' :
 only the z component of axis 3 (v3_z) is moved
            
'xy' :
 only v1_x and v2_y are moved
            
'xz' :
 only v1_x and v3_z are moved
            
'yz' :
 only v2_y and v3_z are moved
            
'xyz' :
 only v1_x, v2_y, v3_z are moved
            
'shape' :
 all axis and angles, keeping the volume fixed
            
'volume' :
 the volume changes, keeping all angles fixed (i.e. only celldm(1) changes)
            
'2Dxy' :
 only x and y components are allowed to change
            
'2Dshape' :
 as above, keeping the area in xy plane fixed
            
BEWARE: if axis are not orthogonal, some of these options do not
        work (symmetry is broken). If you are not happy with them,
        edit subroutine init_dofree in file Modules/cell_base.f90
            

Card: ATOMIC_SPECIES

Syntax:

ATOMIC_SPECIES

Description of items:

X CHARACTER
label of the atom. Acceptable syntax:
chemical symbol X (1 or 2 characters, case-insensitive)
or chemical symbol plus a number or a letter, as in
"Xn" (e.g. Fe1) or "X_*" or "X-*" (e.g. C1, C_h;
max total length cannot exceed 3 characters)
                  
Mass_X REAL
mass of the atomic species [amu: mass of C = 12]
Used only when performing Molecular Dynamics run
or structural optimization runs using Damped MD.
Not actually used in all other cases (but stored
in data files, so phonon calculations will use
these values unless other values are provided)
                  
PseudoPot_X CHARACTER
File containing PP for this species.

The pseudopotential file is assumed to be in the new UPF format.
If it doesn't work, the pseudopotential format is determined by
the file name:

*.vdb or *.van     Vanderbilt US pseudopotential code
*.RRKJ3            Andrea Dal Corso's code (old format)
none of the above  old PWscf norm-conserving format
                  

Card: ATOMIC_POSITIONS { alat | bohr | angstrom | crystal | crystal_sg }

IF calculation == 'bands' OR calculation == 'nscf' :

Specified atomic positions will be IGNORED and those from the
previous scf calculation will be used instead !!!
            

ELSE

Syntax:

ATOMIC_POSITIONS { alat | bohr | angstrom | crystal | crystal_sg }
 X(1)   x(1)   y(1)   z(1)  {  if_pos(1)(1)   if_pos(2)(1)   if_pos(3)(1)  }
 X(2)   x(2)   y(2)   z(2)  {  if_pos(1)(2)   if_pos(2)(2)   if_pos(3)(2)  }
 . . .
 X(nat)   x(nat)   y(nat)   z(nat)  {  if_pos(1)(nat)   if_pos(2)(nat)   if_pos(3)(nat)  }

Description of items:

Card's options: alat | bohr | angstrom | crystal | crystal_sg
Default: (DEPRECATED) alat
Units for ATOMIC_POSITIONS:
            
alat :
atomic positions are in cartesian coordinates, in
units of the lattice parameter (either celldm(1)
or A). If no option is specified, 'alat' is assumed;
not specifying units is DEPRECATED and will no
longer be allowed in the future
            
bohr :
atomic positions are in cartesian coordinate,
in atomic units (i.e. Bohr radii)
            
angstrom :
atomic positions are in cartesian coordinates, in Angstrom
            
crystal :
atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice
vectors as defined either in card CELL_PARAMETERS
or via the ibrav + celldm / a,b,c... variables
            
crystal_sg :
atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice.
This option differs from the previous one because
in this case only the symmetry inequivalent atoms
are given. The variable space_group must indicate
the space group number used to find the symmetry
equivalent atoms. The other variables that control
this option are uniqueb, origin_choice, and
rhombohedral.
            
X CHARACTER
 label of the atom as specified in ATOMIC_SPECIES
                        
x, y, z REAL
atomic positions

NOTE: each atomic coordinate can also be specified as a simple algebraic expression.
      To be interpreted correctly expression must NOT contain any blank
      space and must NOT start with a "+" sign. The available expressions are:

        + (plus), - (minus), / (division), * (multiplication), ^ (power)

      All numerical constants included are considered as double-precision numbers;
      i.e. 1/2 is 0.5, not zero. Other functions, such as sin, sqrt or exp are
      not available, although sqrt can be replaced with ^(1/2).

      Example:
            C  1/3   1/2*3^(-1/2)   0

      is equivalent to

            C  0.333333  0.288675  0.000000

      Please note that this feature is NOT supported by XCrysDen (which will
      display a wrong structure, or nothing at all).

      When atomic positions are of type crystal_sg coordinates can be given
      in the following four forms (Wyckoff positions):
         C  1a
         C  8g   x
         C  24m  x y
         C  48n  x y z
      The first form must be used when the Wyckoff letter determines uniquely
      all three coordinates, forms 2,3,4 when the Wyckoff letter and 1,2,3
      coordinates respectively are needed.

      The forms:
         C 8g  x  x  x
         C 24m x  x  y
      are not allowed, but
         C x x x
         C x x y
         C x y z
      are correct.
                        
if_pos(1), if_pos(2), if_pos(3) INTEGER
Default: 1
component i of the force for this atom is multiplied by if_pos(i),
which must be either 0 or 1.  Used to keep selected atoms and/or
selected components fixed in MD dynamics or
structural optimization run.

With crystal_sg atomic coordinates the constraints are copied in all equivalent
atoms.
                           

Card: K_POINTS { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }

IF tpiba OR crystal OR tpiba_b OR crystal_b OR tpiba_c OR crystal_c :

Syntax:

K_POINTS tpiba | crystal | tpiba_b | crystal_b | tpiba_c | crystal_c
nks  
 xk_x(1)   xk_y(1)   xk_z(1)   wk(1) 
 xk_x(2)   xk_y(2)   xk_z(2)   wk(2) 
 . . .
 xk_x(nks)   xk_y(nks)   xk_z(nks)   wk(nks) 
ELSEIF automatic :

Syntax:

K_POINTS automatic
nk1  nk2  nk3  sk1  sk2  sk3  
ELSEIF gamma :

Syntax:

K_POINTS gamma

Description of items:

Card's options: tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c
Default: tbipa
K_POINTS options are:
            
tpiba :
read k-points in cartesian coordinates,
in units of 2 pi/a (default)
            
automatic :
automatically generated uniform grid of k-points, i.e,
generates ( nk1, nk2, nk3 ) grid with ( sk1, sk2, sk3 ) offset.
nk1, nk2, nk3 as in Monkhorst-Pack grids
k1, k2, k3 must be 0 ( no offset ) or 1 ( grid displaced
by half a grid step in the corresponding direction )
BEWARE: only grids having the full symmetry of the crystal
        work with tetrahedra. Some grids with offset may not work.
            
crystal :
read k-points in crystal coordinates, i.e. in relative
coordinates of the reciprocal lattice vectors
            
gamma :
use k = 0 (no need to list k-point specifications after card)
In this case wavefunctions can be chosen as real,
and specialized subroutines optimized for calculations
at the gamma point are used (memory and cpu requirements
are reduced by approximately one half).
            
tpiba_b :
Used for band-structure plots.
k-points are in units of  2 pi/a.
nks points specify nks-1 lines in reciprocal space.
Every couple of points identifies the initial and
final point of a line. pw.x generates N intermediate
points of the line where N is the weight of the first point.
            
crystal_b :
As tpiba_b, but k-points are in crystal coordinates.
            
tpiba_c :
Used for band-structure contour plots.
k-points are in units of  2 pi/a. nks must be 3.
3 k-points k_0, k_1, and k_2 specify a rectangle
in reciprocal space of vertices k_0, k_1, k_2,
k_1 + k_2 - k_0: k_0 + \alpha (k_1-k_0)+
\beta (k_2-k_0) with 0 <\alpha,\beta < 1.
The code produces a uniform mesh n1 x n2
k points in this rectangle. n1 and n2 are
the weights of k_1 and k_2. The weight of k_0
is not used.
            
crystal_c :
As tpiba_c, but k-points are in crystal coordinates.
            
nks INTEGER
 Number of supplied special k-points.
                     
xk_x, xk_y, xk_z, wk REAL
Special k-points (xk_x/y/z) in the irreducible Brillouin Zone
(IBZ) of the lattice (with all symmetries) and weights (wk)
See the literature for lists of special points and
the corresponding weights.

If the symmetry is lower than the full symmetry
of the lattice, additional points with appropriate
weights are generated. Notice that such procedure
assumes that ONLY k-points in the IBZ are provided in input

In a non-scf calculation, weights do not affect the results.
If you just need eigenvalues and eigenvectors (for instance,
for a band-structure plot), weights can be set to any value
(for instance all equal to 1).
                        
nk1, nk2, nk3 INTEGER
These parameters specify the k-point grid
(nk1 x nk2 x nk3) as in Monkhorst-Pack grids.
                     
sk1, sk2, sk3 INTEGER
The grid offsets;  sk1, sk2, sk3 must be
0 ( no offset ) or 1 ( grid displaced by
half a grid step in the corresponding direction ).
                     

Card: CELL_PARAMETERS { alat | bohr | angstrom }

Optional card, needed only if ibrav == 0 is specified, ignored otherwise !

Syntax:

CELL_PARAMETERS { alat | bohr | angstrom }
 v1(1)   v1(2)   v1(3) 
 v2(1)   v2(2)   v2(3) 
 v3(1)   v3(2)   v3(3) 

Description of items:

Card's options: alat | bohr | angstrom
Unit for lattice vectors; options are:

'bohr' / 'angstrom':
                     lattice vectors in bohr-radii / angstrom.
                     In this case the lattice parameter alat = sqrt(v1*v1).

'alat' / nothing specified:
                     lattice vectors in units of the lattice parameter (either
                     celldm(1) or A). Not specifying units is DEPRECATED
                     and will not be allowed in the future.

If neither unit nor lattice parameter are specified,
'bohr' is assumed - DEPRECATED, will no longer be allowed
         
v1, v2, v3 REAL
Crystal lattice vectors (in cartesian axis):
    v1(1)  v1(2)  v1(3)    ... 1st lattice vector
    v2(1)  v2(2)  v2(3)    ... 2nd lattice vector
    v3(1)  v3(2)  v3(3)    ... 3rd lattice vector
                  

Card: CONSTRAINTS

Optional card, used for constrained dynamics or constrained optimisations (only if ion_dynamics=='damp' or 'verlet', variable-cell excepted)

When this card is present the SHAKE algorithm is automatically used.
      

Syntax:

CONSTRAINTS
nconstr   { constr_tol   }
 constr_type(1)   constr(1)(1)   constr(2)(1)  [  constr(3)(1)    constr(4)(1)   ] {  constr_target(1)  }
 constr_type(2)   constr(1)(2)   constr(2)(2)  [  constr(3)(2)    constr(4)(2)   ] {  constr_target(2)  }
 . . .
 constr_type(nconstr)   constr(1)(nconstr)   constr(2)(nconstr)  [  constr(3)(nconstr)    constr(4)(nconstr)   ] {  constr_target(nconstr)  }

Description of items:

nconstr INTEGER
 Number of constraints.
               
constr_tol REAL
 Tolerance for keeping the constraints satisfied.
                  
constr_type CHARACTER
Type of constraint :
                     
'type_coord' :
constraint on global coordination-number, i.e. the
average number of atoms of type B surrounding the
atoms of type A. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
                     
'atom_coord' :
constraint on local coordination-number, i.e. the
average number of atoms of type A surrounding a
specific atom. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
                     
'distance' :
constraint on interatomic distance
(two atom indexes must be specified).
                     
'planar_angle' :
constraint on planar angle
(three atom indexes must be specified).
                     
'torsional_angle' :
constraint on torsional angle
(four atom indexes must be specified).
                     
'bennett_proj' :
constraint on the projection onto a given direction
of the vector defined by the position of one atom
minus the center of mass of the others.
G. Roma, J.P. Crocombette: J. Nucl. Mater. 403, 32 (2010)
                     
constr(1), constr(2), constr(3), constr(4)
These variables have different meanings for different constraint types:

'type_coord' :
               constr(1) is the first index of the atomic type involved
               constr(2) is the second index of the atomic type involved
               constr(3) is the cut-off radius for estimating the coordination
               constr(4) is a smoothing parameter

'atom_coord' :
               constr(1) is the atom index of the atom with constrained coordination
               constr(2) is the index of the atomic type involved in the coordination
               constr(3) is the cut-off radius for estimating the coordination
               constr(4) is a smoothing parameter

'distance' :
               atoms indices object of the constraint, as they appear in
               the ATOMIC_POSITIONS card

'planar_angle', 'torsional_angle' :
               atoms indices object of the constraint, as they appear in the
               ATOMIC_POSITIONS card (beware the order)

'bennett_proj' :
               constr(1) is the index of the atom whose position is constrained.
               constr(2:4) are the three coordinates of the vector that specifies
               the constraint direction.
                  
constr_target REAL
Target for the constrain ( angles are specified in degrees ).
This variable is optional.
                     

Card: OCCUPATIONS

Optional card, used only if occupations == 'from_input', ignored otherwise !

Syntax:

OCCUPATIONS
 f_inp1(1)   f_inp1(2)   . . .  f_inp1(nbnd) 
[    f_inp2(1)   f_inp2(2)   . . .  f_inp2(nbnd)    ]

Description of items:

f_inp1 REAL
Occupations of individual states (MAX 10 PER ROW).
For spin-polarized calculations, these are majority spin states.
                  
f_inp2 REAL
Occupations of minority spin states (MAX 10 PER ROW)
To be specified only for spin-polarized calculations.
                     

Card: ATOMIC_FORCES

Optional card used to specify external forces acting on atoms.

BEWARE: if the sum of external forces is not zero, the center of mass of
        the system will move
      

Syntax:

ATOMIC_FORCES
 X(1)   fx(1)   fy(1)   fz(1) 
 X(2)   fx(2)   fy(2)   fz(2) 
 . . .
 X(nat)   fx(nat)   fy(nat)   fz(nat) 

Description of items:

X CHARACTER
 label of the atom as specified in ATOMIC_SPECIES
                  
fx, fy, fz REAL
external force on atom X (cartesian components, Ry/a.u. units)
                  
This file has been created by helpdoc utility on Mon Oct 03 17:51:20 CEST 2016.