TABLE OF CONTENTS
INTRODUCTION
Line-of-input: title_line
&INPUTPH
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)
qPointsSpecs
nqs | xq1 | xq2 | xq3 | nq
Line-of-input: atom(1) atom(2) ... atom(nat_todo)
ADDITIONAL INFORMATION
INTRODUCTION
Input data format: { } = optional, [ ] = it depends, # = comment
Structure of the input data:
===============================================================================
title_line
&INPUTPH
...
/
[ 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
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Syntax:
title_line
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Description of items:
title_line |
CHARACTER |
Title of the job, i.e., a line that is reprinted on output.
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|
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Namelist: &INPUTPH
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amass(i), i=1,ntyp |
REAL |
Default: |
0.0
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Atomic mass [amu] of each atomic type.
If not specified, masses are read from data file.
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outdir |
CHARACTER |
Default: |
value of the ESPRESSO_TMPDIR environment variable if set;
current directory ('./') otherwise
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Directory containing input, output, and scratch files;
must be the same as specified in the calculation of
the unperturbed system.
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prefix |
CHARACTER |
Default: |
'pwscf'
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Prepended to input/output filenames; must be the same
used in the calculation of unperturbed system.
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niter_ph |
INTEGER |
Default: |
maxter=100
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Maximum number of iterations in a scf step. If you want
more than 100, edit variable "maxter" in PH/phcom.f90
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tr2_ph |
REAL |
Default: |
1e-12
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Threshold for self-consistency.
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alpha_mix(niter) |
REAL |
Default: |
alpha_mix(1)=0.7
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Mixing factor (for each iteration) for updating
the scf potential:
vnew(in) = alpha_mix*vold(out) + (1-alpha_mix)*vold(in)
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nmix_ph |
INTEGER |
Default: |
4
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Number of iterations used in potential mixing.
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verbosity |
CHARACTER |
Default: |
'default'
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Options are:
- 'debug', 'high', 'medium' :
verbose output
- 'low', 'default', 'minimal' :
short output
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reduce_io |
LOGICAL |
Default: |
.false.
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Reduce I/O to the strict minimum.
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max_seconds |
REAL |
Default: |
1.d7
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Maximum allowed run time before the job stops smoothly.
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fildyn |
CHARACTER |
Default: |
'matdyn'
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File where the dynamical matrix is written.
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fildrho |
CHARACTER |
Default: |
' '
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File where the charge density responses are written.
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fildvscf |
CHARACTER |
Default: |
' '
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File where the the potential variation is written
(for later use in electron-phonon calculation).
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epsil |
LOGICAL |
Default: |
.false.
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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.
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lrpa |
LOGICAL |
Default: |
.false.
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If .true. the dielectric constant is calculated at the
RPA level with DV_xc=0.
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lnoloc |
LOGICAL |
Default: |
.false.
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If .true. the dielectric constant is calculated without
local fields, i.e. by setting DV_H=0 and DV_xc=0.
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trans |
LOGICAL |
Default: |
.true.
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If .true. the phonons are computed.
If trans .and. epsil are .true. effective charges are
calculated.
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lraman |
LOGICAL |
Default: |
.false.
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If .true. calculate non-resonant Raman coefficients
using second-order response as in:
M. Lazzeri and F. Mauri, PRL 90, 036401 (2003).
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Optional variables for Raman:
eth_rps |
REAL |
Default: |
1.0d-9
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Threshold for calculation of Pc R |psi>.
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eth_ns |
REAL |
Default: |
1.0e-12
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Threshold for non-scf wavefunction calculation.
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dek |
REAL |
Default: |
1.0e-3
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Delta_xk used for wavefunction derivation wrt k.
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recover |
LOGICAL |
Default: |
.false.
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If .true. restart from an interrupted run.
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low_directory_check |
LOGICAL |
Default: |
.false.
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If .true. search in the phsave directory only the
quantities requested in input.
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only_init |
LOGICAL |
Default: |
.false.
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If .true. only the bands and other initialization quantities are calculated.
(used for GRID parallelization)
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qplot |
LOGICAL |
Default: |
.false.
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If .true. a list of q points is read from input.
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q2d |
LOGICAL |
Default: |
.false.
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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.
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q_in_band_form |
LOGICAL |
Default: |
.false.
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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.
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electron_phonon |
CHARACTER |
Default: |
' '
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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.
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lshift_q |
LOGICAL |
Default: |
.false.
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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.
|
zeu |
LOGICAL |
Default: |
zeu=epsil
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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.
|
zue |
LOGICAL |
Default: |
.false.
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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.
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elop |
LOGICAL |
Default: |
.false.
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If .true. calculate electro-optic tensor.
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fpol |
LOGICAL |
Default: |
.false.
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If .true. calculate dynamic polarizabilities
Requires epsil=.true. ( experimental stage:
see example09 for calculation of methane ).
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ldisp |
LOGICAL |
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.
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nogg |
LOGICAL |
Default: |
.false.
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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.
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ldiag |
LOGICAL |
Default: |
.false.
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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.
|
lqdir |
LOGICAL |
Default: |
.false.
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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.
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search_sym |
LOGICAL |
Default: |
.true.
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Set it to .false. if you want to disable the mode
symmetry analysis.
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nq1, nq2, nq3 |
INTEGER |
Default: |
0,0,0
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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.
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nk1, nk2, nk3, k1, k2, k3 |
INTEGER |
Default: |
0,0,0,0,0,0
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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.
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Specification of irreducible representation
nat_todo |
INTEGER |
Default: |
0, i.e. displace all atoms
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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.
IMPORTANT:
* 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
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modenum |
INTEGER |
Default: |
0
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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.
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q-point specification
dvscf_star |
STRUCTURE |
Default: |
disabled
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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.
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drho_star |
STRUCTURE |
Default: |
disabled
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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.
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IF ldisp != .true. and qplot != .true. :
Line of input
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Syntax:
xq(1) xq(2) xq(3)
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Description of items:
xq(1) xq(2) xq(3)
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REAL |
The phonon wavevector, in units of 2pi/a0
(a0 = lattice parameter).
Not used if ldisp=.true. or qplot=.true.
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|
|
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ELSEIF qplot == .true. :
Specification of q points when qplot == .true.
Card: qPointsSpecs |
Syntax:
|
Description of items:
nqs |
INTEGER |
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)
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nq |
INTEGER |
The weight of the q-point; the meaning of nq depends
on the flags q2d and q_in_band_form.
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IF nat_todo was specified :
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ADDITIONAL INFORMATION
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
information.
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