Dear Xirainbow: Thank you very much for your reply. What is "relax of phonon calculation? My purpose was the relax calculation before doing calculation of frequency.
Message: 1Date: Sun, 2 Jun 2013 19:07:20 +0800 From: xirainbow <[email protected]> Subject: Re: [Pw_forum] phonon calculation To: Banafshe Noori <b_noori88 at yahoo.com>, PWSCF Forum ??? <pw_forum at pwscf.org> Message-ID: ??? <CABBv2WJG3M5aiQc_nsSi6BcebE4oF2_yop42qNEs0Jrz-9vJ1Q at mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Dear Banafshe Noori : > can i use of press_conv_thr? for a relax of phonon calculation? ? ? ? ? ? ? What is "relax of phonon calculation"? You can even do phonon with experimental crystal lattices and atomic positions without any relaxation. > and why the stress on my system is too high?(-40kbar) ? ? ? ? ? Take the output structure of pw.x as an input and relax it again and again. > What parameters do I need to be changed to reduce stress? ? ? ? ? ? ? Reduce press_conv_thr. On Sun, Jun 2, 2013 at 2:36 PM, Banafshe Noori <b_noori88 at yahoo.com> wrote: > Dear Xirainbow > > thank alot for your respond. > > I search in the input file of pwscf and saw that the is applied for a > vc-relax calculation. > can i use of press_conv_thr? for a relax of phonon calculation? > and why the stress on my system is too high?(-40kbar) > What parameters do I need to be changed to reduce stress? > > > > > > Dear Banafshe Noori : >? ? ? ? ? ? press_conv_thr is the parameter to control the final stress. >? ? ? ? ? ? The default value for press_conv_thr is? 0.5D0 Kbar, which > is good enough for most condition. > > On Sat, Jun 1, 2013 at 11:45 PM, Banafshe Noori <b_noori88 at yahoo.com> > wrote: >> Dear all >> >> I want to calculate phonon frequency. I did a relax for my system(carbon >> nanotube) and saw that? the stress (Kbar) for this system is around >> (-40Kbar). How can i decrease the stress on my system, and for an >> acceptable >> magnitude of ferquencey,? how much be the stress on system.? >> -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130603/99d303c3/attachment.html
