[Wien] Surface Layer Optimization

[Peter Blaha]

You should first optimize theoretically the bulk lattice parameter and use
this value for the slab.
Then use the forces and relax the surface layers of your slab. Do not
change supercell lattice parameters of the slab.
>   I have a question about slab (surface) calculation. I first do a slab
> with a its bulk lattice constant (even between the surface layer and
> the one next to it).
>   Of course, this is an approximation by ignoring the shift of the
> surface layer from its bulk position. Then I try to do structural
> optimization by shifting the surface layer away from its bulk
> position. Do I use the same volume of the unit cell the (then
> vacuum spacing changed) or the same vacuum spacing (then
> the volume of the unit cell changed)? Do I read the total energy
> in case.scf to determine the optimized surface layer position,
> or I need a different definition of the total energy for optimization?
>
> Thank you
> Chiung-Yuan
>
>
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>


                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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