Dear Paolo, Thanks for pointig that out! So if I use the real space representation of the periodic wavefunction (from cft_wave(evc)) with correct igk and later multiply them by exp?ikr?and integrate in a real space volume, they should give me the orthogonality for different k k'?
Thanks a lot, Bo On Oct 31, 2013 6:07 AM, "Paolo Giannozzi" <paolo.giannozzi at uniud.it> wrote: > Bloch states at different k are orthogonal because they have different > k, not because their periodic parts are orthogonal, so your test is not > a valid one. Note that you have to take into account the different > ordering of plane waves (array igk) at k and k' when computing > <k| something |k'> > > P. > > On Thu, 2013-10-31 at 02:13 -0400, Bo Qiu wrote: > > Dear developers and users, > > > > > > I'm trying to compute some matrix elements between states k and k'. To > > confirm my calculation, I first try to compute the overlap between > > wavefunction k and k' as < k| k'> in quantum espresso by taking zdoc > > of state k and k' (modified the elphonon.f90 code). I do find for the > > same k point, the overlap between different bands are 0. However, the > > overlap between two states at different points k and k' are almost > > always non-zero, indicating they're not orthogonal. I thought in > > theory they should all be orthonormal because they belong to the same > > Hamiltonian of the entire system. So is it because of numerical > > reasons that they're actually not orthogonal in quantum espresso? > > > > > > Thanks a lot for you help! > > > > > > Bo > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://pwscf.org/mailman/listinfo/pw_forum > > -- > Paolo Giannozzi, Dept. Chemistry&Physics&Environment, > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20131031/d6c845f8/attachment.html
