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[durandur@engin.umich.edu]

Dear Abinit users,

I am a new user. I am trying to calculate bulk modulus of NaCl.
I used the Troullier-Martins pseudopotentials, a cutoff of
from 20 to 75 Ha and a grid of from 8x8x8 to 15x15x15 kpoints.
The calculations, regardless of used the cutoff and grid, give
the same value of 35 GPa, which is larger than experimental value
of 26 GPa.

I will be glad if you can help me.

Thanks,

Murat Durandurdu

Here one of the inputfiles is:


# NaCl  optimization
#

#Definition of the unit cell
acell 5.264 5.264 5.264 angstrom  # This is equivalent to  1 1 1
angdeg  90 90 90

#Definition of the atom types
ntype 2           # There are three types of atom
znucl 11  17       # The keyword "znucl" refers to the atomic number


pspcod=1
#Definition of the atoms
natom 8           # There are two atoms
type 1 1 1 1 2 2 2 2

xangst              # This keyword indicate that the location of the atoms
2.632 2.632 0
2.632 0 2.632
0 2.632 2.632
0 0 0
0 0 2.632
0 2.632 0
2.632 0 0
2.632 2.632 2.632
#
#Definition of the k-point grids
                  # into account the symmetry
kptopt   1              # K-points will be provided
ngkpt 8 8 8



#Definition of the planewave basis set
ecut  50.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 100          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference
                  # between two consecutive evaluations of total energy
                  # differ by less than toldfe (in Hartree)

enunit 1
ntime  1000
ecotsm=0.5
ionmov 3