The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <xavier.gonze@uclouvain.be>]

Dear Joe,

On 03 Nov 2008, at 18:32, Josef Zwanziger wrote:

> Dear Colleagues,
>
> before I and a colleague here embark on a huge long series of phonon
> calculations, I'd like to get the following clarified:
>
> in anaddb, when analyzing phonons, two input variables are brav and  
> ngqpt. For
> a moderately low symmetry cell, for example monoclinic, I'm assuming  
> that brav
> should be set to 1 (actually, for any symmetry other than fcc, bcc,  
> or hex, is
> that right?)

Yes.

> Secondly, in general for low symmetry the suggested kpt grids from
> prtkpt 1 are not simply ngkpt n1 n2 n3 type, but are expressed with  
> more
> complicated 3X3 kptrlatt variables. In this case, how do you input  
> ngqpt
> properly for anaddb?

Unfortunately, ANADDB is not as flexible that the main ABINIT for the  
treatment
of the q point grids ... The brav input variable allows to compensate  
somehow this lack of flexibility
for the FCC, BCC and hexagonal lattices. But for the time being you  
will have to live with the
usual n1 n2 n3 kpt grids ...

Best regards,
Xavier
> thanks for your help,
>
> Joe Zwanziger