phonon

Phonons, DFPT, electron-phonon, electric-field response, mechanical response…

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bmalvandi
Posts: 21
Joined: Sat Feb 20, 2010 1:42 pm

phonon

Post by bmalvandi » Wed Apr 07, 2010 6:53 am

hello
I want to calculate the phonon for LaCoO3 but not in cubic structure, I want to calculate it in rhombohedral phase
but i don't know how the input variables change?
please help me
thanks

#Response-function calculation, with q=0
rfphon 1 # Will consider phonon-type perturbation
rfatpol 1 2 # All the atoms will be displaced
rfdir 1 1 1 # Along all reduced coordinate axis
nqpt 1 # One wavevector is to be considered
qpt 0 0 0 # This wavevector is q=0 (Gamma)
kptopt 2 # Automatic generation of k points, taking
# into account the time-reversal symmetry only
tolvrs 1.0d-8 # SCF stopping criterion
iscf 5 # Self-consistent calculation, using algorithm 5
irdwfk 1 # Read the ground-state wavefunctions

boudali
Posts: 2
Joined: Thu Apr 08, 2010 12:44 am

Re: phonon

Post by boudali » Thu Apr 29, 2010 5:13 pm

Does the entry sheet is exact.Il stops before completing the output file.
thank you
# Crystalline LaAlO3 : computation of the response to homogeneous
# electric field and atomic displacements, at q=0
#

ndtset 3

#Ground state calculation
kptopt1 1 # Automatic generation of k points, taking
# into account the symmetry
tolvrs1 1.0d-18 # SCF stopping criterion
iscf1 5 # Self-consistent calculation, using algorithm 5

#Response Function calculation : d/dk
rfelfd2 2 # Activate the calculation of the d/dk perturbation
rfdir2 1 0 0 # Need to consider the perturbation in the x-direction only
# This is rather specific, due to the high symmetry of the AlAs crystal
# In general, just use rfdir 1 1 1
# In the present version of ABINIT (v4.6), symmetry cannot be used
# to reduce the number of ddk perturbations

nqpt2 1
qpt2 0.0 0.0 0.0 # This is a calculation at the Gamma point

getwfk2 -1 # Uses as input the output wf of the previous dataset

kptopt2 2 # Automatic generation of k points,
# using only the time-reversal symmetry to decrease
# the size of the k point set.

iscf2 -3 # The d/dk perturbation must be treated
# in a non-self-consistent way
tolwfr2 1.0d-22 # Must use tolwfr for non-self-consistent calculations
# Here, the value of tolwfr is very low.

#Response Function calculation : electric field perturbation and phonons
rfphon3 1 # Activate the calculation of the atomic dispacement perturbations
rfatpol3 1 2 # All the atoms will be displaced
rfelfd3 3 # Activate the calculation of the electric field perturbation
rfdir3 1 1 1 # All directions are selected. However, symmetries will be used to decrease
# the number of perturbations, so only the x electric field is needed
# (and this explains why in the second dataset, rfdir was set to 1 0 0).

nqpt3 1
qpt3 0.0 0.0 0.0 # This is a calculation at the Gamma point

getwfk3 -2 # Uses as input wfs the output wfs of the dataset 1
getddk3 -1 # Uses as input ddk wfs the output of the dataset 2

kptopt3 2 # Automatic generation of k points,
# using only the time-reversal symmetry to decrease
# the size of the k point set.
tolvrs3 1.0d-8
iscf3 5 # Self-consistent calculation, using algorithm 5


#######################################################################
#Common input variables

#Definition of the unit cell

acell 1.0164647896E+01 1.0272740231E+01 1.4435239984E+01 Bohr

rprim 1.0000000000E+00 0.0000000000E+00 0.0000000000E+00
0.0000000000E+00 1.0000000000E+00 0.0000000000E+00
0.0000000000E+00 0.0000000000E+00 1.0000000000E+00
#Definition of the atom types

ntypat 3 # There are two types of atom
znucl 57 13 8 # The keyword "znucl" refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the "files" file must correspond
# to the type(s) of atom. Here, type 1 is the Aluminum,
# type 2 is the Arsenic.

#Definition of the atoms

natom 20

typat 1 1 1 1 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3

xred 1.0782632134E-03 2.7532471986E-07 2.5000000000E-01
5.0107826321E-01 4.9999972468E-01 -2.5000000000E-01
-1.0782632134E-03 -2.7532471975E-07 7.5000000000E-01
4.9892173679E-01 5.0000027532E-01 2.5000000000E-01
5.0000000000E-01 5.5511151231E-17 0.0000000000E+00
1.0000000000E+00 5.0000000000E-01 0.0000000000E+00
-5.0000000000E-01 5.5511151231E-17 5.0000000000E-01
-1.3877787808E-17 5.0000000000E-01 5.0000000000E-01
2.4999864940E-01 2.5000215779E-01 2.0158647769E-02
7.4999864940E-01 2.4999784221E-01 -2.0158647769E-02
-2.4999864940E-01 -2.5000215779E-01 5.2015864777E-01
2.5000135060E-01 7.5000215779E-01 4.7984135223E-01
-2.4999864940E-01 -2.5000215779E-01 -2.0158647769E-02
2.5000135060E-01 7.5000215779E-01 2.0158647769E-02
2.4999864940E-01 2.5000215779E-01 4.7984135223E-01
7.4999864940E-01 2.4999784221E-01 5.2015864777E-01
5.3919168635E-01 -1.4814265884E-08 2.5000000000E-01
1.0391916864E+00 5.0000001481E-01 -2.5000000000E-01
-5.3919168635E-01 1.4814265981E-08 7.5000000000E-01
-3.9191686353E-02 4.9999998519E-01 2.5000000000E-01

#Gives the number of band, explicitely (do not take the default)
nband 67 # For an insulator (if described correctly as an insulator
# by DFT), there is no need to include conduction bands
# in response-function calculations

#Exchange-correlation functional
ixc 23

#Definition of the planewave basis set
ecut 3.0

#Definition of the k-point grid
kptrlatt 6 0 0 0 6 0 0 0 4

#Definition of the SCF procedure

nstep 20
diemac 6.0

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