[Wien] Diamond lattice

Michael Frotscher frotscher at chemie.uni-hamburg.de
Mon Jan 5 16:44:09 CET 2004

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Dear Dr. Blaha,

Thank you for your answer. I already figured out that origin choice two must 
be used instead of using (1/4,1/4,1/4), which really doesn't make sense.

> However, in this setting all matrix elements in a calculation would be
> complex numbers and the calculation would take 4x as long and need 2x
> memory.
> Thus WIEN2k REQUIRES to use a setting where inversion is at the origin of
> the cell.

Ah, ok. I was wondering why it was done this way. So whenever there is more 
than one choice of origin, WIEN uses the one with the inversion center (if 
present) at (0,0,0)?

> What do you learn from this: The name of the spacegroup + some coordinates
> of an atom are sometimes NOT sufficient to describe a structure. You must
> either also specify which "setting" of the spacegroup was chosen or
> specify which Wyckoff position was given (and from this you know which
> setting was used).

True. It would help, though, if w2web would show the Wyckoff-Positions for the 
atoms entered - in this case I would probably have seen it right away.

Maybe something for the wish-list, don't you think?

- -- 
Michael Frotscher
Institute of Inorganic and Applied Chemistry
University of Hamburg, Germany 
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