[Pw_forum] terahedra method for projwfc

[Paolo Giannozzi]

On Thu, 2015-03-19 at 12:40 +0100, Ludwig, Stephan wrote:

> I read that the tetrahedron method is not implemented for
> projwfc-calculations.

> What does this mean?

What part of "not implemented" don't you understand ... ?

I have answered questions on PDOS and tetrahedra many times.
I am quite sure that there are implementations of it around, 
but nobody has ever spent a few minutes of his/her precious 
time to make it public. Once again:
http://www.mail-archive.com/pw_forum%40pwscf.org/msg20466.html
"projwfc.x cannot calculate PDOS with tetrahedra, if I remember
correctly. More exactly: it could, provided somebody take the 
existing code that calculates the PDOS for phonons (it should 
be routine dos_gam in matdyn.f90), adapts it to electrons"

http://www.mail-archive.com/pw_forum%40pwscf.org/msg20509.html
"My advice is to look at the attached notes, look at the dos_gam 
routine in PHonon/PH/matdyn.f90, implement PDOS with tetrahedra"

> I have done scf calculation with gaussian smearing and afterwards nscf
> calculations with tedrahedra ( wanted to calculate DOS).
> 
> Now I want to obtain the PDOS. When I do not specify any occupation
> and smearing and degauss in the projwfc-file I do not receive any
> error messages.
> 
> I suppose the program chooses some default values (gaussian smearing
> etc. Which defaults are chosen?).

it is documented in the input documentation

> My question: Is it a good idea to use a nscf-calculation with
> tetrahedra-method to calculate PDOS or shall I repeat the nscf with
> gaussian smearing?

the results of a nscf calculation does not depend upon the choice of
gaussian broadening or tetrahedra. Only weights are computed in a 
different way, but if you cannot use tetrahedra for PDOS, you have 
to provide a gaussian broadening to the projwfc.x code if none is
provided in the nscf calculation

Paolo
> Thanks and regards,
> 
> 
> Stephan
> 
> 
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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