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ask for help about the GW calculation of band gap

From: lbo@ustc.edu
To: forum@abinit.org
Subject: ask for help about the GW calculation of band gap
Date: Tue, 11 Jan 2005 08:59:59 +0100

Dear ABINIT experts,

I have difficulty in GW calculation for correction of band gap .
I an not sure how to set the parameters in GW calculation.
I appreciate for any help!

I have done the band structure calculation for PbFCl.
The result shows the direct gap at Z point in BZ.
The toppest valence band is 28 and the lowest conduction band is 29.
I would like to using GW calculation the correction of the band gap between
the
band of 28 and 29.
I consulted the example for the case of Si given by the program.

My input files is following:

#Definition of the unit cell
acell 7.841 7.841 13.81
rprim 1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.0

#Definition of the atom types
ntypat 3
znucl 9 17 82

#Definition of the atoms
natom 6
typat 1 1 2 2 3 3
xred

0.0 0.0 0.0
0.5 0.5 0.0
0.0 0.5 0.65
0.5 0.0 0.35
0.0 0.5 0.2
0.5 0.0 0.8

#Definition of the planewave basis set
ecut 15.0

# Definition of the SCF procedure
nstep 30
toldfe 1.0d-6
diemac 12.0

# Definition of the k-point grid
kptopt 1

nkpt 6
ngkpt 4 4 4
nshiftk 1

shiftk 0.5 0.5 0.5

# Definition of parameters for the calculation of the KSS file
nband 35
nbndsto -1
ncomsto 0

ndtset 3

# Calculation of the screening (epsilon^-1 matrix)
optdriver2 3
getkss2 -1
nband2 35
npwwfn2 85
npweps2 169
plasfrq2 16.7 eV

# Calculation of the Self-Energy matrix elements (GW corrections)
optdriver3 4
getkss3 -2
geteps3 -1
nband3 100
npwwfn3 133
npwmat3 169

ngwpt3 1
kptgw3
0.0 0.000 0.500 # Z point
bdgw3 28 29
zcut3 0.1 eV

The log file shows an error as below

identifying k-points
number of k-points in irreducible wedge (IBZ) 6
k-points [reciprocal lattice units] weights
1 0.125000 0.125000 0.125000 0.500000
2 0.375000 0.125000 0.125000 1.000000
3 0.375000 0.375000 0.125000 0.500000
4 0.125000 0.125000 0.375000 0.500000
5 0.375000 0.125000 0.375000 1.000000
6 0.375000 0.375000 0.375000 0.500000
together with the 8 symmetry operations and inversion
have yielded 64 k-points in Brillouin Zone (BZ):
1 0.125 0.125 0.125 0.125-0.125 0.125 -0.125-0.125 0.125 -0.125 0.125
0.125
5-0.125-0.125-0.125 -0.125 0.125-0.125 0.125 0.125-0.125
0.125-0.125-0.125
9 0.375 0.125 0.125 0.375-0.125 0.125 -0.375-0.125 0.125 -0.375 0.125
0.125
13-0.125-0.375-0.125 -0.125 0.375-0.125 0.125 0.375-0.125
0.125-0.375-0.125
17-0.375-0.125-0.125 -0.375 0.125-0.125 0.375 0.125-0.125
0.375-0.125-0.125
21 0.125 0.375 0.125 0.125-0.375 0.125 -0.125-0.375 0.125 -0.125 0.375
0.125
25 0.375 0.375 0.125 0.375-0.375 0.125 -0.375-0.375 0.125 -0.375 0.375
0.125
29-0.375-0.375-0.125 -0.375 0.375-0.125 0.375 0.375-0.125
0.375-0.375-0.125
33 0.125 0.125 0.375 0.125-0.125 0.375 -0.125-0.125 0.375 -0.125 0.125
0.375
37-0.125-0.125-0.375 -0.125 0.125-0.375 0.125 0.125-0.375
0.125-0.125-0.375
41 0.375 0.125 0.375 0.375-0.125 0.375 -0.375-0.125 0.375 -0.375 0.125
0.375
45-0.125-0.375-0.375 -0.125 0.375-0.375 0.125 0.375-0.375
0.125-0.375-0.375
49-0.375-0.125-0.375 -0.375 0.125-0.375 0.375 0.125-0.375
0.375-0.125-0.375
53 0.125 0.375 0.375 0.125-0.375 0.375 -0.125-0.375 0.375 -0.125 0.375
0.375
57 0.375 0.375 0.375 0.375-0.375 0.375 -0.375-0.375 0.375 -0.375 0.375
0.375
61-0.375-0.375-0.375 -0.375 0.375-0.375 0.375 0.375-0.375
0.375-0.375-0.375

timing point number 50
-cpu time = 1.17 seconds
-real time = 1.17 seconds

check if the k-points for sigma are in the set of BZ
**error findk 1: k-point not in the set of kbz;

I wonder how to change the input parameters.
Thank you very much for any help!

sincerely
Bo Liu
lbo@ustc.edu

ask for help about the GW calculation of band gap, lbo, 01/11/2005
- Re: [abinit-forum] ask for help about the GW calculation of band gap, Fabien Bruneval, 01/11/2005