Input File Description

Program: ph.x / PWscf / Quantum Espresso (version: 6.1)



Line-of-input: title_line


amass | outdir | prefix | niter_ph | tr2_ph | alpha_mix(niter) | nmix_ph | verbosity | reduce_io | max_seconds | fildyn | fildrho | fildvscf | epsil | lrpa | lnoloc | trans | lraman | eth_rps | eth_ns | dek | recover | low_directory_check | only_init | qplot | q2d | q_in_band_form | electron_phonon | lshift_q | zeu | zue | elop | fpol | ldisp | nogg | ldiag | lqdir | search_sym | nq1 | nq2 | nq3 | nk1 | nk2 | nk3 | k1 | k2 | k3 | start_irr | last_irr | nat_todo | modenum | start_q | last_q | dvscf_star | drho_star

Line-of-input: xq(1) xq(2) xq(3)


nqs | xq1 | xq2 | xq3 | nq

Line-of-input: atom(1) atom(2) ... atom(nat_todo)



Input data format: { } = optional, [ ] = it depends, # = comment

Structure of the input data:



[ xq(1) xq(2) xq(3) ]                        # if ldisp != .true.  and  qplot != .true.

[ nqs                                        # if qplot == .true. 
  xq(1,i)    xq(2,i)    xq(3,1)    nq(1)
  xq(1,nqs)  xq(2,nqs)  xq(3,nqs)  nq(nqs) ]

[ atom(1)  atom(2)  ... atom(nat_todo) ]     # if nat_todo was specified

Line of input



Description of items:

title_line CHARACTER
Title of the job, i.e., a line that is reprinted on output.

Namelist: &INPUTPH

amass(i), i=1,ntyp REAL
Default: 0.0
Atomic mass [amu] of each atomic type.
If not specified, masses are read from data file.
Default: value of the ESPRESSO_TMPDIR environment variable if set;
current directory ('./') otherwise
Directory containing input, output, and scratch files;
must be the same as specified in the calculation of
the unperturbed system.
Default: 'pwscf'
Prepended to input/output filenames; must be the same
used in the calculation of unperturbed system.
niter_ph INTEGER
Default: maxter=100
Maximum number of iterations in a scf step. If you want
more than 100, edit variable "maxter" in PH/phcom.f90
tr2_ph REAL
Default: 1e-12
 Threshold for self-consistency.
alpha_mix(niter) REAL
Default: alpha_mix(1)=0.7
Mixing factor (for each iteration) for updating
the scf potential:

vnew(in) = alpha_mix*vold(out) + (1-alpha_mix)*vold(in)
nmix_ph INTEGER
Default: 4
 Number of iterations used in potential mixing.
verbosity CHARACTER
Default: 'default'
 Options are:
'debug', 'high', 'medium' :
 verbose output
'low', 'default', 'minimal' :
 short output
reduce_io LOGICAL
Default: .false.
 Reduce I/O to the strict minimum.
max_seconds REAL
Default: 1.d7
 Maximum allowed run time before the job stops smoothly.
Default: 'matdyn'
 File where the dynamical matrix is written.
Default: ' '
 File where the charge density responses are written.
fildvscf CHARACTER
Default: ' '
File where the the potential variation is written
(for later use in electron-phonon calculation).
Default: .false.
If .true. in a q=0 calculation for a non metal the
macroscopic dielectric constant of the system is
computed. Do not set epsil to .true. if you have a
metallic system or q/=0: the code will complain and stop.
Default: .false.
If .true. the dielectric constant is calculated at the
RPA level with DV_xc=0.
lnoloc LOGICAL
Default: .false.
If .true. the dielectric constant is calculated without
local fields, i.e. by setting DV_H=0 and DV_xc=0.
Default: .true.
If .true. the phonons are computed.
If trans .and. epsil are .true. effective charges are
lraman LOGICAL
Default: .false.
If .true. calculate non-resonant Raman coefficients
using second-order response as in:
M. Lazzeri and F. Mauri, PRL 90, 036401 (2003).

Optional variables for Raman:

eth_rps REAL
Default: 1.0d-9
 Threshold for calculation of  Pc R |psi>.
eth_ns REAL
Default: 1.0e-12
 Threshold for non-scf wavefunction calculation.
dek REAL
Default: 1.0e-3
 Delta_xk used for wavefunction derivation wrt k.
recover LOGICAL
Default: .false.
 If .true. restart from an interrupted run.
low_directory_check LOGICAL
Default: .false.
If .true. search in the phsave directory only the
                 quantities requested in input.
only_init LOGICAL
Default: .false.
If .true. only the bands and other initialization quantities are calculated.
(used for GRID parallelization)
Default: .false.
 If .true. a list of q points is read from input.
Default: .false.
If .true. three q points and relative weights are
read from input. The three q points define the rectangle
q(:,1) + l (q(:,2)-q(:,1)) + m (q(:,3)-q(:,1)) where
0< l,m < 1. The weights are integer and those of points two
and three are the number of points in the two directions.
q_in_band_form LOGICAL
Default: .false.
This flag is used only when qplot is .true. and q2d is
.false.. When .true. each couple of q points q(:,i+1) and
q(:,i) define the line from q(:,i) to q(:,i+1) and nq
points are generated along that line. nq is the weigth of
q(:,i). When .false. only the list of q points given as
input is calculated. The weights are not used.
electron_phonon CHARACTER
Default: ' '
Options are:
'simple' :
Electron-phonon lambda coefficients are computed
for a given q and a grid of k-points specified by
the variables nk1, nk2, nk3, k1, k2, k3.
'interpolated' :
Electron-phonon is calculated by interpolation
over the Brillouin Zone as in M. Wierzbowska, et
al. arXiv:cond-mat/0504077
'lambda_tetra' :
The electron-phonon coefficient \lambda_{q \nu}
is calculated with the optimized tetrahedron method.
'gamma_tetra' :
The phonon linewidth \gamma_{q \nu} is calculated
from the electron-phonon interactions
using the optimized tetrahedron method.
For metals only, requires gaussian smearing.

If trans=.true., the lambdas are calculated in the same
run, using the same k-point grid for phonons and lambdas.
If trans=.false., the lambdas are calculated using
previously saved DeltaVscf in fildvscf, previously saved
dynamical matrix, and the present punch file. This allows
the use of a different (larger) k-point grid.
lshift_q LOGICAL
Default: .false.
Use a wave-vector grid displaced by half a grid step
in each direction - meaningful only when ldisp is .true.
When this option is set, the q2r.x code cannot be used.
Default: zeu=epsil
If .true. in a q=0 calculation for a non metal the
effective charges are computed from the dielectric
response. This is the default algorithm. If epsil=.true.
and zeu=.false. only the dielectric tensor is calculated.
Default: .false.
If .true. in a q=0 calculation for a non metal the
effective charges are computed from the phonon
density responses. This is an alternative algorithm,
different from the default one (if trans .and. epsil )
The results should be the same within numerical noise.
Default: .false.
If .true. calculate electro-optic tensor.
Default: .false.
If .true. calculate dynamic polarizabilities
Requires epsil=.true. ( experimental stage:
see example09 for calculation of methane ).
Default: .false.
If .true. the run calculates phonons for a grid of
q-points specified by nq1, nq2, nq3 - for direct
calculation of the entire phonon dispersion.
Default: .false.
If .true. disable the "gamma_gamma" trick used to speed
up calculations at q=0 (phonon wavevector) if the sum over
the Brillouin Zone includes k=0 only. The gamma_gamma
trick exploits symmetry and acoustic sum rule to reduce
the number of linear response calculations to the strict
minimum, as it is done in code phcg.x. This option MUST
BE USED if a run with ph.x is to be followed by a run
with d3.x for third-order terms calculation.
Default: .false.
If .true. forces the diagonalization of the dynamical
matrix also when only a part of the dynamical matrix
has been calculated. It is used together with start_irr
and last_irr. If all modes corresponding to a
given irreducible representation have been calculated,
the phonon frequencies of that representation are
correct. The others are zero or wrong. Use with care.
Default: .false.
If .true. ph.x creates inside outdir a separate subdirectory
for each q vector. The flag is set to .true. when ldisp=.true.
and fildvscf /= ' ' or when an electron-phonon
calculation is performed. The induced potential is saved
separately for each q inside the subdirectories.
search_sym LOGICAL
Default: .true.
Set it to .false. if you want to disable the mode
symmetry analysis.
nq1, nq2, nq3 INTEGER
Default: 0,0,0
Parameters of the Monkhorst-Pack grid (no offset) used
when ldisp=.true. Same meaning as for nk1, nk2, nk3
in the input of pw.x.
nk1, nk2, nk3, k1, k2, k3 INTEGER
Default: 0,0,0,0,0,0
When these parameters are specified the phonon program
runs a pw non-self consistent calculation with a different
k-point grid thant that used for the charge density.
This occurs even in the Gamma case.
nk1,nk2,nk3 are the parameters of the Monkhorst-Pack grid
with offset determined by k1,k2,k3.

Specification of irreducible representation

start_irr INTEGER
Default: 1
See: last_irr
Perform calculations only from start_irr to last_irr
irreducible representations.

   * start_irr must be <= 3*nat
   * do not specify nat_todo together with
     start_irr, last_irr
last_irr INTEGER
Default: 3*nat
See: start_irr
Perform calculations only from start_irr to last_irr
irreducible representations.

   * start_irr must be <= 3*nat
   * do not specify nat_todo together with
     start_irr, last_irr
nat_todo INTEGER
Default: 0, i.e. displace all atoms
Choose the subset of atoms to be used in the linear response
calculation: nat_todo atoms, specified in input (see below)
are displaced. Can be used to estimate modes for a molecule
adsorbed over a surface without performing a full fledged
calculation. Use with care, at your own risk, and be aware
that this is an approximation and may not work.
   * nat_todo <= nat
   * if linear-response is calculated for a given atom, it
     should also be done for all symmetry-equivalent atoms,
     or else you will get incorrect results
modenum INTEGER
Default: 0
For single-mode phonon calculation : modenum is the index of the
irreducible representation (irrep) into which the reducible
representation formed by the 3*nat atomic displacements are
decomposed in order to perform the phonon calculation.
Note that a single-mode calculation will not give you the
frequency of a single phonon mode: in general, the selected
"modenum" is not an eigenvector. What you get on output is
a column of the dynamical matrix.

q-point specification

start_q INTEGER
Default: 1
See: last_q
Used only when ldisp=.true..
Computes only the q points from start_q to last_q.

   * start_q must be <= nqs (number of q points found)
   * do not specify nat_todo together with
     start_q, last_q
last_q INTEGER
Default: number of q points
See: start_q
Used only when ldisp=.true..
Computes only the q points from start_q to last_q.

   * last_q must be <= nqs (number of q points)
   * do not specify nat_todo together with
     start_q, last_q
dvscf_star STRUCTURE
Default: disabled
It contains the following components:

dvscf_star%open  (logical, default: .false.)
dvscf_star%dir   (character, default: outdir//"Rotated_DVSCF" or the
                  ESPRESSO_FILDVSCF_DIR environment variable)
dvscf_star%ext   (character, default: "dvscf") the extension to use
                  for the name of the output files, see below
dvscf_star%basis (character, default: "cartesian") the basis on which
                  the rotated dvscf will be saved
dvscf_star%pat   (logical, default: false) save an optional file with the
                  displacement patterns and q vector for each dvscf file

IF dvscf_star%open is .true. use symmetry to compute and store the variation
of the self-consistent potential on every q* in the star of the present q.

The rotated dvscf will then be stored in directory dvscf_star%dir with name
prefix.dvscf_star%ext.q_name//"1". Where q_name is derived from the coordinates
of the q-point, expressed as fractions in crystalline coordinates
(notice that ph.x reads q-points in cartesian coordinates).
E.g. q_cryst= (0, 0.5, -0.25) -> q_name = "0_1o2_-1o4"

The dvscf can be represented on a basis of cartesian 1-atom displacements
(dvscf_star%basis='cartesian') or on the basis of the modes at the rotated q-point
(dvscf_star%basis='modes'). Notice that the el-ph wannier code requires 'cartesian'.
Each dvscf file comes with a corresponding pattern file with an additional ".pat"
suffix; this file contains information about the basis and the q-point of the dvscf.

Note: rotating dvscf can require a large amount of RAM memory and can be i/o
      intensive; in its current implementation all the operations are done
      on a single processor.
Note2: this feature is currently untested with image parallelisation.
drho_star STRUCTURE
Default: disabled
See: dvscf_star
It contains the following components:

drho_star%open  (logical, default: .false.)
drho_star%dir   (character, default: outdir//"Rotated_DRHO" or the
                 ESPRESSO_FILDRHO_DIR environment variable)
drho_star%ext   (character, default: "drho") the extension to use
                 for the name of the output files, see below
drho_star%basis (character, default: "modes") the basis on which
                 the rotated drho will be saved
drho_star%pat   (logical, default: true) save an optional file with the
                 displacement patterns and q vector for each drho file

Like dvscf_star, but for the perturbation of the charge density.
Notice that the defaults are different.
IF ldisp != .true. and qplot != .true. :

Line of input


xq(1) xq(2) xq(3)   

Description of items:

xq(1) xq(2) xq(3) REAL
The phonon wavevector, in units of 2pi/a0
(a0 = lattice parameter).
Not used if ldisp=.true. or qplot=.true.
ELSEIF qplot == .true. :

Specification of q points when qplot == .true.

Card: qPointsSpecs


 xq1(1)   xq2(1)   xq3(1)   nq(1) 
 xq1(2)   xq2(2)   xq3(2)   nq(2) 
 . . .
 xq1(nqs)   xq2(nqs)   xq3(nqs)   nq(nqs) 

Description of items:

Number of q points in the list. Used only if qplot=.true.
xq1, xq2, xq3 REAL
q-point coordinates; used only with ldisp=.true. and qplot=.true.
The phonon wavevector, in units of 2pi/a0 (a0 = lattice parameter).
The meaning of these q points and their weights nq depend on the
flags q2d and q_in_band_form. (NB: nq is integer)
The weight of the q-point; the meaning of nq depends
on the flags q2d and q_in_band_form.
IF nat_todo was specified :

Line of input


atom(1) atom(2) ... atom(nat_todo)   

Description of items:

atom(1) atom(2) ... atom(nat_todo) INTEGER
Contains the list of indices of atoms used in the
calculation if nat_todo is specified.


NB: The program ph.x writes on the tmp_dir/_ph0/{prefix}.phsave directory
a file for each representation of each q point. This file is called
dynmat.#iq.#irr.xml where #iq is the number of the q point and #irr
is the number of the representation. These files contain the
contribution to the dynamical matrix of the irr representation for the
iq point.

If recover=.true. ph.x does not recalculate the
representations already saved in the tmp_dir/_ph0/{prefix}.phsave
directory.  Moreover ph.x writes on the files patterns.#iq.xml in the
tmp_dir/_ph0/{prefix}.phsave directory the displacement patterns that it
is using. If recover=.true. ph.x does not recalculate the
displacement patterns found in the tmp_dir/_ph0/{prefix}.phsave directory.

This mechanism allows:

  1) To recover part of the ph.x calculation even if the recover file
     or files are corrupted. You just remove the _ph0/{prefix}.recover
     files from the tmp_dir directory. You can also remove all the _ph0
     files and keep only the _ph0/{prefix}.phsave directory.

  2) To split a phonon calculation into several jobs for different
     machines (or set of nodes). Each machine calculates a subset of
     the representations and saves its dynmat.#iq.#irr.xml files on
     its tmp_dir/_ph0/{prefix}.phsave directory. Then you collect all the
     dynmat.#iq.#irr.xml files in one directory and run ph.x to
     collect all the dynamical matrices and diagonalize them.

NB: To split the q points in different machines, use the input
variables start_q and last_q. To split the irreducible
representations, use the input variables start_irr, last_irr. Please
note that different machines will use, in general, different
displacement patterns and it is not possible to recollect partial
dynamical matrices generated with different displacement patterns.  A
calculation split into different machines will run as follows: A
preparatory run of ph.x with start_irr=0, last_irr=0 produces the sets
of displacement patterns and save them on the patterns.#iq.xml files.
These files are copied in all the tmp_dir/_ph0/{prefix}.phsave directories
of the machines where you plan to run ph.x. ph.x is run in different
machines with complementary sets of start_q, last_q, start_irr and
last_irr variables.  All the files dynmat.#iq.#irr.xml are
collected on a single tmp_dir/_ph0/{prefix}.phsave directory (remember to
collect also dynmat.#iq.0.xml).  A final run of ph.x in this
machine collects all the data contained in the files and diagonalizes
the dynamical matrices.  This is done requesting a complete dispersion
calculation without using start_q, last_q, start_irr, or last_irr.
See an example in examples/GRID_example.

On parallel machines the q point and the irreps calculations can be split
automatically using the -nimage flag. See the phonon user guide for further
This file has been created by helpdoc utility on Fri Mar 03 06:56:17 UTC 2017.