Hi all,
I am doing a calculation on bulk InAs, and I am using LDA pseudo-
potentials downloaded from the SIESTA website -- the ones imported
from Abinit. I am using In pseudo-potential with semicore.
After I converged the mesh cut-off (200 Ry) and the kpoints
(Monkhorst pack 20*20*16) -- I am using a 4 atom cell (for the
diamond structure), hence longer lattice vector in z-direction.
I relaxed the lattice constant variationally, and found it to be far
too small: 3.4951 Ang, as compared with the experimental value of
4.2840 Ang. Also the gap found from the DOS plot is about 4eV, which
is also way too large.
I am using automatically generated DZP basis for As, with energy
shift of 100 meV. The pseudopotential of As gives a ghost at l=3, so
I have restricted PS.lmax for As to 2 (d shells.).
For In, since it has semicore, I need to define the basis by hand,
and here are the parameters:
PAO.BasisSize DZP
PAO.EnergyShift 100 meV
%block PS.lmax
In 3
As 2
%endblock PS.lmax
%block PAO.Basis
In 3
n=4 2 2 P
0.00 0.00
1.00 1.00
n=5 0 2
0.00 0.00
1.00 1.00
n=5 1 2
0.00 0.00
1.00 1.00
%endblock PAO.Basis
I left the cut-off radii to 0.0 so that they will be generated by the
code automatically. And I have added a polarisation orbital to the
4d shell.
I thought these parameters were reasonable... but the results show
otherwise. Either the pseudo-potential is bad or I am using a bad
basis. Please could anyone give me any suggestions in how to improve
the calculations?
Thank you very much!
Lianheng
