GGA+U

[dilna]

Haii,

Tried the GGA+U calculation for CuBr. But the GGA+U band gap value is only slightly greater thane the GGA gap value.( 0.45 eV for GGA and 0.49 eV for GGA+U). If I use the same U and J value in VASP, getting a large GGA+U gap (1.5 eV ) compared to the GGA gap(0.357 eV). Can anyone suggest a solution for this??

Here is the elk.in file.

tasks
0

xctype
20

lda+u
3 1 : ldapu,inptypelu
1 2 0.257248907 0.055124766 : is,llu(is),ujlu(1,is),ujlu(2,is)

dos
9000 100 1
0 0.18

swidth
0.001

ngridk
20 20 20
vkloff
0.625 0.5 0.25

nempty
15

avec
0.000000000 1.000000000 1.000000000
1.000000000 0.000000000 1.000000000
1.000000000 1.000000000 0.000000000

scale
5.407668648

sppath
'../../../ELK_code/elk-2.2.9/species/'

atoms
2 : nspecies
'Cu.in' : spfname
1 : natoms
0.0 0.0 0.0 0.0 0.0 0.0 : atposl, bfcmt
'Br.in' : spfname
1 : natoms
0.25 0.25 0.25 0.0 0.0 0.0 : atpos1, bfcmt

[Sangeeta Sharma]

I am not able to reproduce your results. I get a large vaöue of gap using GGA+U.

Could you please run calculations using the following input file? Also please use only the latest version of the code. Version 2.2.9 is old and might have a bug.

tasks
1

xctype
20

dft+u
1 1 : dftu,inpdftu
1 2 0.257248907 0.055124766

swidth
0.001

dos
1000 100 1
0 0.5

ngridk
06 06 06

vkloff
0.625 0.5 0.25

nempty
5

avec
0.00000000 5.37674328 5.37674328
5.37674328 0.00000000 5.37674328
5.37674328 5.37674328 0.00000000

atoms
2 : nspecies
'Cu.in' : spfname
1
0.0 0.0 0.0 0.0 0.0 0.0 : atposl, bfcmt
'Br.in' : spfname
1 : natoms
0.25 0.25 0.25 0.0 0.0 0.0 : atpos1, bfcmt

[dilna]

Thank you for the reply.