[Wien] Re: total energy question

[Stefaan Cottenier]

> Your answer implies that Wien2k writes the structure
> into the .struc file in terms of primitive unit cells.
> Is this an absolute principle?  Meaning, if I set
> up a cell as a conventional fcc cell in StrucGen will
> the positions, lattice constants, etc. be converted by
> wien2k to primitive cell when writing to .struc?
> What if I set up a cell as a conventional fcc unit
> cell directly in .struc?

For F- and B-type (or I-type) lattices, the conventional lattice constants
are used in case.struct, but only one atom position needs to be given (see
sec. 4.3, explanation about line 4 of the UG). Hence, yes, case.struct is
always about the primitive cell (but makes it easier for you by accepting
conventional lattice constants for F and B). If you would insist on
specifying 2 atoms for a body centred lattice (000 and 1/2,1/2,1/2), you
have to select a P-type lattice (with B, you would have 2 atoms at each
site, and obviously errors/crashes). In such a case, sgroup will suggest you
to change to B and only 1 atom. Similarly for fcc.

Stefaan