Input File Description

Program: bands.x / PWscf / Quantum ESPRESSO (version: 7.2)




prefix | outdir | filband | spin_component | lsigma | lp | filp | lsym | no_overlap | plot_2d | firstk | lastk


Purpose of bands.x:
   Re-order bands, computes band-related properties. Currently,
   re-ordering can be done with two different algorithms:
   (a) by maximising the overlap with bands at previous k-point
   (b) by computing symmetry properties of each wavefunction
   Bands-related properties that can be computed are currently
   (a) The expectation value of the spin operator on each spinor
       wave-function (noncolinear case only)
   (b) The expectation value of p

The input data can be read from standard input or from file using
command-line options "bands.x -i file-name" (same syntax as for pw.x)

Output files:
- file filband containing the band structure, in a format
  suitable for plotting code "plotband.x"
- file "filband".rap (if lsym is .t.)  with symmetry information,
  to be read by plotting code "plotband.x"
- if (lsigma(i)): file "filband".i, i=1,2,3, with expectation values
  of the spin operator in the noncolinear case
- file "filband".gnu with bands in eV, directly plottable using gnuplot
- file filp with matrix elements of p (including the nonlocal potential
  contribution i*m*[V_nl,x])

Structure of the input data:


Namelist: &BANDS

Default: 'pwscf'
prefix of files saved by program pw.x
Default: value of the ESPRESSO_TMPDIR environment variable if set; current directory ('./') otherwise
directory containing the input data, i.e. the same as in pw.x
Default: 'bands.out'
file name for band output (to be read by "plotband.x")
spin_component INTEGER
In the lsda case select:

   1 = spin-up
   2 = spin-down
lsigma(i), i=1,3 LOGICAL
If true computes expectation values of the spin operator
on the spinor wave-functions (only in the noncollinear case),
writes them to a file "filband".i, i=1,2,3
Default: .false.
If .true. matrix elements of the momentum operator p between
conduction and valence bands are computed and written to file
specified in filp.
The matrix elements include the contribution from the nonlocal
potential, i*m*[V_nl, x]. In other words, the calculated matrix elements
are those of the velocity operator i*m*[H, x] times mass, not those of
the true momentum operator.
Default: 'p_avg.dat'
If lp is set to .true., file name for matrix elements of p
Default: .true.
If .true. the bands are classified according to the
irreducible representations of the small group of k.
A file "filband".rap with the same format of "filband"
is written, for usage by "plotband.x"
no_overlap LOGICAL
Default: .true.
If .false., and if lsym is .false., writes the eigenvalues
in the order that maximises overlap with the neighbor k-points
plot_2d LOGICAL
Default: .false.
If .true. writes the eigenvalues in the output file
in a 2D format readable by gnuplot. Band ordering is not
changed. Each band is written in a different file called
filband.# with the format:

   xk, yk, energy
   xk, yk, energy
   ..  ..  ..

energies are written in eV and xk in units 2\pi/a.
firstk, lastk INTEGER
if lsym=.true. makes the symmetry analysis only for k
points between firstk to lastk
This file has been created by helpdoc utility on Thu Mar 30 12:14:01 CEST 2023.