[Pw_forum] factional co-ordinate input to QE

[janardhan H.L.]

Dear all,

Giving input to QE as a slab is relatively easy and for bulk material it is usually done by converting cif files to readable xyz formats, cif files give only the irreducible coordinates which are obtained by fitting the experimental data. My question is on the second method, in many of the cases atomic positions are of fractional occupancy if we reproduce the complete unit cell by applying the symmetric operations it may lead different atomic co-ordinates. Example of zinchydroxystannate is attached, in this case both the hydrogen have 0.5 occ, by converting to xyz format by VESTA it gave a unit cell where the oxygen have 2 hydrogen but it is not true as it is the 0.5 occ for both hydrogen, in this case if I give occ of 1 for one of the hydrogen it is not the representative structure of the compound. So what is the best method to be followed to give a correct input of the following structure.
with thanks and regards
Janardhan L. HodalaClean energy catalysis labKIST,  S. Korea

 
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