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ABout Phonon cal of BaTiO3

From: Devidas Gulwade <devidas@met.iitb.ac.in>
To: forum@abinit.org
Subject: ABout Phonon cal of BaTiO3
Date: Mon, 15 Mar 2004 16:13:55 +0530 (IST)

Dear ABINTS

I am facing some difficulty regarding the gamma phonon calculations
I have tried with the following i/p file, kindly suggest me how to
improve?

I/P file

#Definition of cell
#**********************************
prtvol 10
acell 3*7.55890395431569
#Definition of atoms
#*********************
natom 5
ixc 1
ntypat 3
spgroup 221
typat 1 2 3 3 3
natrd 3
xred
0.0 0.0 0.0
0.5 0.5 0.5
0.5 0.5 0.0
znucl 56 22 8
#******************************
nstep 90
#************************************
ecut 45
ndtset 4
#####################################################
DATA SET 1 : GS Calculation
#####################################################
kptopt1 1
prtden1 1
nqpt1 0
#prtwf1 1
#prtgeo1 1
#prtvhxc1 1
tolvrs1 1.0d-22
#getden1 0
#getwfk1 0
iscf1 3
##################################################
#DATASET 2 : non scf calculation: GS WF in the whole BZ
#*****************************************************
kptopt2 3
nqpt2 0
getden2 1
iscf2 -3
getwfk2 1
tolwfr2 1.0d-22
#prtwf2 1
##################################################
#DATASET 3 : ddk on the MP grid of k-points
###################################################
getwfk3 1
getddk3 3
nqpt3 1
qpt3 0 0 0
rfdir3 1 1 1
rfelfd3 2
tolwfr3 1.0d-22
kptopt3 3
iscf3 -3
######################################################
#***************************************************
getwfk4 2
getddk4 3
rfdir4 1 1 1
toldfe4 1.0d-12
rfelfd4 3
rfphon4 1
rfatpol4 1 5
kptopt4 3
iscf4 5
nqpt4 1
qpt4 0 0 0
###################################################################
#Common data
##################################################################
enunit 2
amu 1.37327000E+02 4.78800000E+01 1.59994000E+01
rfasr 1
ngkpt 6 6 6
diemac 4
#nspol 2
nband 24

O/P file

== DATASET 1
==================================================================
Components of total free energy (in Hartree) :

Kinetic energy = 4.44150236543295E+01
Hartree energy = 1.44554808364963E+01
XC energy =-2.03805700239665E+01
Ewald energy =-5.90125855167467E+01
PspCore energy = 1.70587945714044E+01
Loc. psp. energy=-5.69019097998285E+01
NL psp energy=-1.13633824476377E+01
>>>>>>>>> Etotal=-7.17291487259492E+01

Other information on the energy :
Total energy(eV)=-1.95184936693742E+03 ; Band energy (Ha)=
-1.4878070510E+01
--------------------------------------------------------------------------------

================================================================================
== DATASET 2
==================================================================

mkfilename : getwfk/=0, take file _WFK from output of DATASET 1.

mkfilename : getden/=0, take file _DEN from output of DATASET 1.

================================================================================
== DATASET 3
==================================================================

mkfilename : getwfk/=0, take file _WFK from output of DATASET 1.

mkfilename : getddk/=0, take file _1WF from output of DATASET 3.

iter 2DEtotal(Ha) deltaE(Ha) residm vres2

-ETOT 1 -28.457618623697 -2.846E+01 2.526E-01 0.000E+00

ETOT 2 -28.495026483338 -3.741E-02 1.480E-01 0.000E+00

ETOT 3 -28.495281050524 -2.546E-04 4.733E-02 0.000E+00

ETOT 4 -28.495283776952 -2.726E-06 9.838E-02 0.000E+00

ETOT 5 -28.495283813145 -3.619E-08 3.507E-02 0.000E+00

ETOT 6 -28.495283813682 -5.364E-10 9.521E-02 0.000E+00

ETOT 7 -28.495283813690 -8.097E-12 3.529E-02 0.000E+00

ETOT 8 -28.495283813690 -2.665E-13 1.057E-01 0.000E+00

ETOT 9 -28.495283813690 -8.438E-14 3.429E-02 0.000E+00

ETOT 10 -28.495283813690 7.816E-14 1.112E-01 0.000E+00

ETOT 11 -28.495283813690 1.386E-13 3.339E-02 0.000E+00

ETOT 12 -28.495283813690 -9.504E-14 1.111E-01 0.000E+00

ETOT 13 -28.495283813690 2.309E-14 3.263E-02 0.000E+00

ETOT 14 -28.495283813690 -1.776E-14 1.115E-01 0.000E+00

ETOT 15 -28.495283813690 0.000E+00 3.203E-02 0.000E+00

ETOT 16 -28.495283813690 -2.665E-15 1.123E-01 0.000E+00

ETOT 17 -28.495283813690 3.553E-15 3.158E-02 0.000E+00

ETOT 18 -28.495283813690 -3.553E-15 Z.132E-01 0.000E+00

ETOT 19 -28.495283813690 -5.329E-15 3.123E-02 0.000E+00

ETOT 20 -28.495283813690 -1.066E-14 1.142E-01 0.000E+00

ETOT 21 -28.495283813690 -2.665E-15 3.096E-02 0.000E+00

ETOT 22 -28.495283813690 2.665E-15 1.153E-01 0.000E+00

ETOT 23 -28.495283813690 -1.776E-15 3.075E-02 0.000E+00

ETOT 24 -28.495283813690 7.994E-15 1.164E-01 0.000E+00

ETOT 25 -28.495283813690 -6.217E-15 3.058E-02 0.000E+00

ETOT 26 -28.495283813690 7.105E-15 1.176E-01 0.000E+00

ETOT 27 -28.495283813690 -2.665E-15 3.045E-02 0.000E+00

ETOT 28 -28.495283813690 1.776E-15 1.188E-01 0.000E+00

ETOT 29 -28.495283813690 -8.882E-16 3.034E-02 0.000E+00

ETOT 30 -28.495283813690 -1.776E-15 1.201E-01 0.000E+00

ETOT 31 -28.495283813690 5.329E-15 3.025E-02 0.000E+00

ETOT 32 -28.495283813690 2.665E-15 1.214E-01 0.000E+00

The phonon frequnecies calculated for same i/p file but with ngkpt 4 4 4

Phonon frequencies in cm-1 :
- -3.628571E+00 -3.611971E+00 -3.537227E+00 2.237433E+02 2.237433E+02
- 2.237487E+02 3.277369E+02 3.277369E+02 3.277369E+02 3.309412E+02
- 3.309415E+02 3.309416E+02 6.747113E+02 6.747135E+02 6.747138E+02
does not match with the reported data.

And it end up with same kind of problems that resdm does not get minimised
even after 140-150 cycles and keep dangling inbetween 1d-1 to 1d-2
I am under the impression that my structure of i/p file is good enough, if
not so and appearently If I have misunderstood somehting then please

help me in this regard.

Earlier I have tried GS calculations for 90 nstep and found that, for
diemac above 3 to 8 converge the energy in minimum steps as compare to the
lower values and within the appreciable value of ETOT, However I did not
undersatnd the physical significance of Microscopic dielectric constant.

I have tried the i/p nsppol 2, but it end up with same problems(any
suggestions on usage of the same for insulators).

Kindly guide me to move further, and let me know If I have misunderstood
something. Let me if I need to include some more variable for spin
polrization
but I found by going through the Ph. Ghosez thesis that it should not give
that much difference.

Thanking you for kind cooperation

With regards and best wisehes
Devidas

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Whatever our mind conceives and believes, we can acheive.

Devidas
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abinit.4.1.4+ifc8+mkl, sayede adlane, 03/15/2004
- ABout Phonon cal of BaTiO3, Devidas Gulwade, 03/15/2004