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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.

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.