PAW files and lattice constants
Posted: Fri May 20, 2011 10:10 am
Hi: I am trying to generate some PAW files.
It is not working as expected for some elements, and as a test, I went back to the basics.
I tried to get the equilibrium lattice constants reported in the 'ABINIT table' for PAW data, for the elements C, N and O, using the PAW files of the table.
This went smoothly for C, but I failed with N and O. The calculated lattice constants are 5-10% larger than the reported values.
I am puzzled by this result and I would appreciate any suggestions.
Best Regards,
Jacques
List of elements-structure, PAW file, ecut, cell parameter in a.u.(reported and calculated values).
C-dia, C-LDA-hard-uspp, 17 Ha, reported: 6.69, calculated: 6.69.
N-FCC, N-LDA-hard-uspp, 15 Ha, reported: 5.76, calculated: 6.37.
O-FCC, O-LDA-hard-uspp, 16 Ha, reported: 5.80, calculated: 6.13.
# input file - equilibrium lattice constants
# abinit-6.6.2
# O - FCC
ndtset 11
acell: 3*5.30
acell+ 3*0.1
rprim 0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
ntypat 1
znucl 8
natom 1
typat 1
xred 0. 0. 0.
ecut 16.0
pawecutdg 40.0
ecutsm 0.5
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
ngkpt 7 7 7
ixc 2
tolvrs 1.0d-14
nstep 50
It is not working as expected for some elements, and as a test, I went back to the basics.
I tried to get the equilibrium lattice constants reported in the 'ABINIT table' for PAW data, for the elements C, N and O, using the PAW files of the table.
This went smoothly for C, but I failed with N and O. The calculated lattice constants are 5-10% larger than the reported values.
I am puzzled by this result and I would appreciate any suggestions.
Best Regards,
Jacques
List of elements-structure, PAW file, ecut, cell parameter in a.u.(reported and calculated values).
C-dia, C-LDA-hard-uspp, 17 Ha, reported: 6.69, calculated: 6.69.
N-FCC, N-LDA-hard-uspp, 15 Ha, reported: 5.76, calculated: 6.37.
O-FCC, O-LDA-hard-uspp, 16 Ha, reported: 5.80, calculated: 6.13.
# input file - equilibrium lattice constants
# abinit-6.6.2
# O - FCC
ndtset 11
acell: 3*5.30
acell+ 3*0.1
rprim 0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
ntypat 1
znucl 8
natom 1
typat 1
xred 0. 0. 0.
ecut 16.0
pawecutdg 40.0
ecutsm 0.5
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
ngkpt 7 7 7
ixc 2
tolvrs 1.0d-14
nstep 50