[Q-e-developers] wavefunction

Nicola Marzari nicola.marzari at epfl.ch
Wed Oct 28 12:46:11 CET 2015

On 28/10/2015 14:22, Jiqiang Li wrote:
> 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?

No - you can choose one arbitrary phase exp (i.alpha_n,k) for every
u_n,k(r); but only at Gamma you can choose an alpha_n,Gamma
so that u_n,k (r) is real everywhere (i.e. for every r).

This is to say that the u_n,k (r) are intrinsically complex,
while u_n,Gamma (r), if it comes out complex, it is so trivially,
and there is a single phase that makes u_n,Gamma (r) everywhere real.


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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