Purpose of matdyn.x:
This program calculates the phonon frequencies for a list of generic
q vectors starting from the interatomic force constants generated
from the dynamical matrices as written by DFPT phonon code through
the companion program q2r.xmatdyn.x can generate a supercell of the original cell for mass
approximation calculation. If supercell data are not specified
in input, the unit cell, lattice vectors, atom types and positions
are read from the force constant file.
Input data format: [ ] = it depends
Structure of the input data:
========================================================================
&INPUT
...specs of the namelist variables...
/
[ X(1) Y(1) Z(1) ityp(1)
...
X(nat) Y(nat) Z(nat) ityp(nat) ]
[ nq
q_x(1) q_y(1) q_x(1) [ nptq(1) ]
...
q_x(nq) q_y(nq) q_x(nq) [ nptq(1) ] ]
File produced by q2r containing force constants (needed)
It is the same as in the input of q2r.x (+ the .xml extension
if the dynamical matrices produced by ph.x were in xml
format). No default value: must be specified.
'no'
Indicates the type of Acoustic Sum Rule imposed.
Allowed values:
no Acoustic Sum Rules imposed (default)
previous implementation of the asr used
(3 translational asr imposed by correction of
the diagonal elements of the force constants matrix)
3 translational asr imposed by optimized
correction of the force constants (projection)
3 translational asr + 3 rotational asr + 15 Huang
conditions for vanishing stress tensor, imposed by
optimized correction of the force constants (projection).
Remember to set write_lr = .true. to write long-range
force constants into file when running q2r and set read_lr = .true. when running matdyn in the case of
infrared-active solids. (See npj Comput Mater 8, 236 (2022))
3 translational asr + 1 rotational asr imposed
by optimized correction of the dyn. mat. (the
rotation axis is the direction of periodicity; it
will work only if this axis considered is one of
the Cartesian axis).
3 translational asr + 3 rotational asr imposed
by optimized correction of the dyn. mat.
Note that in certain cases, not all the rotational asr
can be applied (e.g. if there are only 2 atoms in a
molecule or if all the atoms are aligned, etc.).
In these cases the supplementary asr are cancelled
during the orthonormalization procedure (see below).
.true.
if .true. 15 Huang conditions for vanishing stress
tensor are included in asr = 'all'.
if .true. calculate phonon Density of States (DOS)
using tetrahedra and a uniform q-point grid (see below)
NB: may not work properly in noncubic materials
if .false. calculate phonon bands from the list of q-points
supplied in input (default)
uniform q-point grid for DOS calculation (includes q=0)
(must be specified if dos = .true., ignored otherwise)
energy step, in cm-1, for DOS calculation: from min
to max phonon energy (default: 1 cm-1 if ndos, see
below, is not specified)
number of energy steps for DOS calculations
(default: calculated from deltaE if not specified)
DOS broadening in cm-1
Default: 0 - meaning use tetrahedra
output file for dos (default: 'matdyn.dos')
the dos is in states/cm-1 plotted vs omega in cm(-1)
and is normalised to 3*nat, i.e. the number of phonons
output file for frequencies (default: 'matdyn.freq')
output file for normalized phonon displacements
(default: 'matdyn.modes'). The normalized phonon displacements
are the eigenvectors divided by the square root of the mass,
then normalized. As such they are not orthogonal.
output file for phonon eigenvectors (default: 'matdyn.eig')
The phonon eigenvectors are the eigenvectors of the dynamical
matrix. They are orthogonal.
output file for dynamical matrix (default: ' ' i.e. not written)
supercell lattice vectors - must form a superlattice of the
original lattice (default: use original cell)
supercell lattice vectors are original cell vectors times
l1, l2, l3 respectively (default: 1, ignored if at specified)
number of atom types in the supercell
(default: ntyp of the original cell)
masses of atoms in the supercell (a.m.u.), one per atom type
(default: use masses read from file flfrc)
read atomic positions of the supercell from input
(used to specify different masses) (default: .false.)
write atomic positions of the supercell to file fltau
(default: fltau = ' ', do not write)
if .true. interpolates also the el-ph coefficients
if .true. the q points are given in band form:
only the first and last point of one or more lines
are given. See below. (default: .false.).
if .true. input q points are in crystalline
coordinates (default: .false.)
use similarity of the displacements to order
frequencies (default: .false.)NB: You cannot use this option with the symmetry
analysis of the modes.
if .true. the ifc come from the finite displacement calculation
add non analitic contributions to the interatomic force
constants if finite displacement method is used (as in Wang et al.
PRB 85, 224303 (2012)) [to be used in conjunction with fd.x]
if .true., no symmetry and no time reversal are imposed
set to .true. to activate two-dimensional treatment of LO-TO splitting
if .true. do not apply LO-TO splitting for q=0
(default: .false.).false.
if .true. read also long-range force constants when they exist in
force constant file. This is required when enforcing asr = 'all'
for infrared-active solids.
.false.
if .true. write force constants with asr imposed into file.
The filename would be flfrc+".matdyn". The long-range part of
force constants will be not written.
X, Y, Z atomic positions
index of the atomic type
number of q points
The format of the q-points specification is:
(q(i,n),i=1,3), nptq
nptq is the number of points between this point
and the next. These points are automatically
generated. the q points are given in Cartesian
coordinates, 2pi/a units (a = lattice parameters)
coordinates of the Q point
The number of points between this point and the next.
nptq is the number of points between this point
and the next. These points are automatically
generated. the q points are given in Cartesian
coordinates, 2pi/a units (a = lattice parameters)
number of q points
The format of the q-points specification is:
((q(i,n),i=1,3), n=1,nq)
q-points in cartesian coordinates, 2pi/a units (a = lattice parameters)
If q = 0, the direction qhat (q=>0) for the non-analytic part
is extracted from the sequence of q-points as follows:
qhat = q(n) - q(n-1) or qhat = q(n) - q(n+1)
depending on which one is available and nonzero.
For low-symmetry crystals, specify twice q = 0 in the list
if you want to have q = 0 results for two different directions