[Pw_forum] occupations=tedrahedra

[Paolo Giannozzi]

On Mon, 2015-03-16 at 11:34 +0100, Ludwig, Stephan wrote:

> I read it is suggested to use the option "occupations=tedrahedra"
> and "nosym=.true."

"occupations=tedrahedra", yes; "nosym=.true." is (sometimes) used 
for other purposes. If you don't understand it, don't use it.

> in order to calculate DOS. Do I have to use these options just in the
> nscf-run or also in the scf-rund?

in the nscf run only. You shouldn't perform structural optimization 
with tetrahedra.

> And by the way I have difficulties to understand what these options
> mean. All I understand is that tedrahedra inhibits that I miss some
> singularities in DOS. But I do not understand how it works.

see P. E. Bloechl et al, PRB49, 16223 (1994)

Paolo

> 
> 
> Can anybody help me to improve my comrehension?
> 
> 
> 
> Thanks and regards
> 
> 
> 
> Stephan Ludwig
> 
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222