Hello QE developers and users, Recently, I am trying to calculate phonon dispersion of a 2D material using pw.x, ph.x, q2r.x and matdyn.x but I am getting very strange results.
In my calculations the phonon frequencies reported by ph.x are all real for all non-gamma phonon q-points. But, when I use matdyn.x to calculate phonon frequencies at other points (other than the one for which ph.x calculated frequencies), I get negative (imaginary) frequencies. And these negative frequencies are present for non-gamma points as can be seen in attached frequency file. I am having difficulty in understanding these results and hoping someone could help. Thank You, Ankit Jain PhD Candidate IIT India -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: pw.in Type: application/octet-stream Size: 601 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: ph.in Type: application/octet-stream Size: 150 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment-0001.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: q2r.in Type: application/octet-stream Size: 96 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment-0002.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: matdyn.in Type: application/octet-stream Size: 374 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment-0003.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: frequency Type: application/octet-stream Size: 1006 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20140831/de8d7368/attachment-0004.obj
