[Pw_forum] wannier_ham.x: setting up the input file

[Dmitry Korotin]

Dear Wang Riping,


2016-04-22 17:37 GMT+05:00 Wang Riping <wangriping at outlook.com>:
> Dear Prof. Korotin
>
>
> I am going to set the parameter for the input file of wannier_ham.x.
> Thank you very much for last reply.
>
> This following part is copied from the example file for NiO shipped with quantum ESPRESSO:
> WANNIER_AC
>  Wannier# 1 2 9
>  atom 1
>  d 1 1.0
>
> 1. What why it is starting from 2 to 9 orbitals, not from 1 to 9?

The wannier_ham.x code was created to produce a model Hamiltonian for
DMFT calculations i.e. to solve the Hubbard model. For NiO the
correlated electronic states are Ni-d states. In addition one should
consider O-p states since they are strongly hybridised  with Ni-d
states. The Wannier function basis consists of 8 Wannier functions (5
for Ni-d and 3 for O-p). There are no any reason to consider within
DMFT calculation O-s state that corresponds to the first energy band.
That is why we start from the second band and use 8 bands for
projection.

> 2. what is the 1.0 in the last line? How to set it?

There is an undocumented feature in the wannier_ham.x code. One can
perform a projection of Bloch state not on a pure atomic orbital, but
on a linear  combinations of atomic orbitals with the same l. To
generate WF as a sum of two orbitals: 0.75*(3z^2-r^2) + 0.25*(x^2-y^2)
one should create the input for wannier_ham.x code as:
WANNIER_AC
Wannier# 1 2 9 2
atom 1
d 1 0.75
d 4 0.25

In fact if one want to do a simple projection on a pure atomic orbital
the last number of the line
d 1 1.0
could be ommited, i.e one can use as input
WANNIER_AC
Wannier# 1 2 9
atom 1
d 1



>
>
> Thank you very much.
> Wang Riping
> 20164.22
>
>
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-- 


Best regards,
Dr. Dmitry Korotin

Institute of Metal Physics
S. Kovalevskaya, 18
620990 Yekaterinburg
Russia