[Pw_forum] How to generate a pp which is 3/4 of itself using virtual.x

[Eyvaz Isaev]

Dear Jun Dai,

--- On Sun, 10/18/09, Jun Dai <jdai3 at mail.ustc.edu.cn> wrote:
 
> I have a system has 38 oxygen atoms whoes occupation is 3/4, so i want 
> to genrate a new O pp which is 3/4 of itself, 
> can someone give some suggestions on how to do it,

I suggest, the problem has no solution in ab initio calculations. What you mean generating of a new PsP for O (3/4 of O) means to generate a PsP ... for  Carbon. Using virtual.x you can mix PsPs for elements with similar properties or neighbouring elements in the Periodic Table.  

But the problem you post is different: an O position is occupied by the probability of 0.75. I think the problem can not be solved also in the framework of alloy's theory where a site can be occupied in accordance with atomic concentration (but the site occupancy is 1!), say in a substitutional alloy A(1-x)B(x)C, where atoms A and B occupy the same site with weight 1-x and x, respectively.

Hope this helps.

Bests,
Eyvaz.

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com