[Q-e-developers] wavefunction

[Jiqiang Li]

Nicola,
     As you mentioned, the relative phases between wavefunctions at all the k points make no sense. Did you mean we can force the wavefunction at any k points to real as we like?

Jiqiang 



 
From: Nicola Marzari
Date: 2015-10-28 19:17
To: General discussion list for Quantum ESPRESSO developers
Subject: Re: [Q-e-developers] wavefunction
 
 
You are correct - there is a phase at gamma that you can remove
and make all the gamma wavefunctions real.
 
Also, you do not to change the phases at other k-points - the phases at
every k-point are arbitrary.
 
nicola
 
On 28/10/2015 14:11, Jiqiang Li wrote:
> Dear Paolo,
>       Sorry to have expressed the wrong idea.
> 1) I want to ask how to merely force the wavefunction at Gamma point to
> real numbers in a calculation with many k points, I do not care the case
> of other k points. "The former case is implemented", is it implemented?
> However, I output the wavefunction at Gamma point, result shows that
>   wavefunction at Gamma point is complex.
>
> 2)Furthermore, I found that the elements of wavefunction array belong to
> identical k points share the same phase.  Then can I multiply
>   wavefuntions at all k points by the oppsite phase of wavefunction at
> Gamma point. Then the wavefunction at Gamma point becomes real numbers,
> the relative phase between wavefunction at all k points keep unchange
> and physical properties will remain. Correct me if I am wrong.
>
> Jiqiang Li
>
> ------------------------------------------------------------------------
>
>     *From:* Paolo Giannozzi <mailto:p.giannozzi at gmail.com>
>     *Date:* 2015-10-28 17:31
>     *To:* General discussion list for Quantum ESPRESSO developers
>     <mailto:q-e-developers at qe-forge.org>
>     *CC:* jqli14 <mailto:jqli14 at fudan.edu.cn>
>     *Subject:* Re: [Q-e-developers] wavefunction
>     You cannot, in general.  You can choose real wavefunctions only for
>     Gamma (k=0), or if the system has inversion symmetry. The former
>     case is implemented, the latter is not.
>     It wouldn't be that difficult to implement it, but it must be done
>     with care.
>
>     Paolo
>
>     On Wed, Oct 28, 2015 at 8:07 AM, jqli14 <jqli14 at fudan.edu.cn
>     <mailto:jqli14 at fudan.edu.cn>> wrote:
>
>         Dear all,
>               In a calculation with  many  k points, how to force the
>         wavefunctions to real numbers but not complex numbers?
>
>         Jiqiang Li
>
>
>
>
>
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>
>
>
>     --
>     Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
>     Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>     Phone +39-0432-558216 <tel:%2B39-0432-558216>, fax +39-0432-558222
>     <tel:%2B39-0432-558222>
>
>
>
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-- 
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
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