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<div><span></span>Nicola,</div><div> 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?</div><div><br></div><div>Jiqiang </div>
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<blockquote style="margin-top: 0px; margin-bottom: 0px; margin-left: 0.5em;"><div> </div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><div style="PADDING-RIGHT: 8px; PADDING-LEFT: 8px; FONT-SIZE: 12px;FONT-FAMILY:tahoma;COLOR:#000000; BACKGROUND: #efefef; PADDING-BOTTOM: 8px; PADDING-TOP: 8px"><div><b>From:</b> <a href="mailto:nicola.marzari@epfl.ch">Nicola Marzari</a></div><div><b>Date:</b> 2015-10-28 19:17</div><div><b>To:</b> <a href="mailto:q-e-developers@qe-forge.org">General discussion list for Quantum ESPRESSO developers</a></div><div><b>Subject:</b> Re: [Q-e-developers] wavefunction</div></div></div><div><div> </div>
<div> </div>
<div>You are correct - there is a phase at gamma that you can remove</div>
<div>and make all the gamma wavefunctions real.</div>
<div> </div>
<div>Also, you do not to change the phases at other k-points - the phases at</div>
<div>every k-point are arbitrary.</div>
<div> </div>
<div> nicola</div>
<div> </div>
<div>On 28/10/2015 14:11, Jiqiang Li wrote:</div>
<div>> Dear Paolo,</div>
<div>> Sorry to have expressed the wrong idea.</div>
<div>> 1) I want to ask how to merely force the wavefunction at Gamma point to</div>
<div>> real numbers in a calculation with many k points, I do not care the case</div>
<div>> of other k points. "The former case is implemented", is it implemented?</div>
<div>> However, I output the wavefunction at Gamma point, result shows that</div>
<div>> wavefunction at Gamma point is complex.</div>
<div>></div>
<div>> 2)Furthermore, I found that the elements of wavefunction array belong to</div>
<div>> identical k points share the same phase. Then can I multiply</div>
<div>> wavefuntions at all k points by the oppsite phase of wavefunction at</div>
<div>> Gamma point. Then the wavefunction at Gamma point becomes real numbers,</div>
<div>> the relative phase between wavefunction at all k points keep unchange</div>
<div>> and physical properties will remain. Correct me if I am wrong.</div>
<div>></div>
<div>> Jiqiang Li</div>
<div>></div>
<div>> ------------------------------------------------------------------------</div>
<div>></div>
<div>> *From:* Paolo Giannozzi <mailto:p.giannozzi@gmail.com></div>
<div>> *Date:* 2015-10-28 17:31</div>
<div>> *To:* General discussion list for Quantum ESPRESSO developers</div>
<div>> <mailto:q-e-developers@qe-forge.org></div>
<div>> *CC:* jqli14 <mailto:jqli14@fudan.edu.cn></div>
<div>> *Subject:* Re: [Q-e-developers] wavefunction</div>
<div>> You cannot, in general. You can choose real wavefunctions only for</div>
<div>> Gamma (k=0), or if the system has inversion symmetry. The former</div>
<div>> case is implemented, the latter is not.</div>
<div>> It wouldn't be that difficult to implement it, but it must be done</div>
<div>> with care.</div>
<div>></div>
<div>> Paolo</div>
<div>></div>
<div>> On Wed, Oct 28, 2015 at 8:07 AM, jqli14 <jqli14@fudan.edu.cn</div>
<div>> <mailto:jqli14@fudan.edu.cn>> wrote:</div>
<div>></div>
<div>> Dear all,</div>
<div>> In a calculation with many k points, how to force the</div>
<div>> wavefunctions to real numbers but not complex numbers?</div>
<div>></div>
<div>> Jiqiang Li</div>
<div>></div>
<div>></div>
<div>></div>
<div>></div>
<div>></div>
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<div>></div>
<div>></div>
<div>></div>
<div>> --</div>
<div>> Paolo Giannozzi, Dept. Chemistry&Physics&Environment,</div>
<div>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy</div>
<div>> Phone +39-0432-558216 <tel:%2B39-0432-558216>, fax +39-0432-558222</div>
<div>> <tel:%2B39-0432-558222></div>
<div>></div>
<div>></div>
<div>></div>
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<div>></div>
<div> </div>
<div>-- </div>
<div>----------------------------------------------------------------------</div>
<div>Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL</div>
<div>Director, National Centre for Competence in Research NCCR MARVEL, EPFL</div>
<div>http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project</div>
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