[Pw_forum] Use of wannier90.x for the calculation of Born Effective Charge

[Nicola Marzari]

Dear Yukihiro,

not sure if you got an answer (btw, this question might be more suited 
to the
wannier mailing list) - but wouldn't it just require the calculation 
with the
undisplaced Ti to be done with the exact same mesh of the displaced Ti ?

A quick and dirty approach would be moving the Ti by a tiny amount,
that essentially does not change the results for the cubic system, but is
recognized by the code as off axis. Try 0.50001 and 0.500001.

Note that BaTiO3 cubic has zero polarization, although that is not 
always the
case (there is a 2007 review paper by Resta and Vanderbilt on this - 
e.g. from
Vanderbilt's web site).


          nicola

> If we set nosym in the input file of non-SCF calculation with k-points is
> same as
>
> BaTiO3.win file., the symmetry of the results of wannier center
>
> broken, so the calculated Born Effective Charges are wrong.
>
> How should treat the k-points inconsistent when we calculate the Born
> effective
>
> charge in displacing the atom.
>
> Here is my input file for BaTiO3.win.
>   


-- 
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Prof Nicola Marzari   Department of Materials Science and Engineering
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