[Pw_forum] about disordered structures

[Stefano de Gironcoli]

The whole idea of virtual crystal approximation is that one replaces all 
atom of a given disordered sublattice with a pseudopotential which is the 
proper average of the two species that are distributed in that sublattice.
In the upftools directory of the QE distribution there is a simple code
called virtual.x that reads two pseudopotentials in the upf format, a 
mixing fraction, x, and produces a third pseudopotential as (1-x)V1+xV2 .
Then you can use this virtual-atom pseudo as usual in the other QE codes.

This is a feature that as very seldom been used... so test that your 
results make sense before trusting them (even more than usual).

Please report any doubt/problem/bug.
Thank you,

    Stefano de Gironcoli


On Mon, 9 Oct 2006, sun jian wrote:

> Dear all,
>
> whether pwscf can be used to calculate disordered crystals within virtural 
> crystal approximation ? If it can, how to specify the lattice, i.e. atom 
> positions and compositions ?
>
> Thank you very much in advance !
>
> Best regards,
> ===============================================
> Jian SUN Physics Dept. of Nanjing University National Lab. of Solid State 
> Microstructures 22 Hankou Road, Gulou District Nanjing, Jiangsu Province 
> 210093 China ===============================================
>
>
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