How to assign partial occupancy in POSCAR

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Khaqan Shati
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How to assign partial occupancy in POSCAR

#1 Post by Khaqan Shati » Fri Feb 27, 2015 5:38 am

Dear Forum Members,
I want to make a structure with partial atomic occupancy e.g. Bi0.5Sb0.5Te3.
I tried to make the structure in VESTA and assigned occupancy as 0.5 for Bi ad Sb with same coordinates and exported the POSCAR.
But on running the job, I got the error that some atoms are very near to each other, which means POSCAR in this way can not handle the partial occupancy.
Can anyone of you please suggest/help, how to make a POSCAR for such structure which has a partial atomic occupancy.
Thanks.

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Re: How to assign partial occupancy in POSCAR

#2 Post by admin » Fri Feb 27, 2015 10:04 am

Partial occupancies are observed as a result of averaging over the space.
A crystallographic site can be occupied only by a single atom.
To simulate partial occupancy one can use a supercell approach.
For Bi0.5 and Sb0.5 take doubled cell. In the first sub-cell place into
the corresponding site Bi and in the second Sb.

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