It is because you did not finish all the steps to analyse the data. I got a similar problem before and I remember it is possible to obtain a file that has as the vectors of the modes that can be viewed in the xcrysden. Unfortunately I don't run simulations phonon simulations anymore, I couldn't remember everything I did in the past.
I am pasting a manual section that explains it in details. (I also change the color to red the point I think might solve your issue.) 4.2 Calculation of interatomic force constants in real space First, dynamical matrices are calculated and saved for a suitable uniform grid of *q*-vectors (only those in the Irreducible Brillouin Zone of the crystal are needed). Although this can be done one *q*-vector at the time, a simpler procedure is to specify variable ldisp=.true. and to set variables nq1, nq2,nq3 to some suitable Monkhorst-Pack grid, that will be automatically generated, centered at [image: $ \bf q$] = 0 . Second, code q2r.x reads the dynamical matrices produced in the preceding step and Fourier-transform them, writing a file of Interatomic Force Constants in real space, up to a distance that depends on the size of the grid of *q*-vectors. Input documentation in the header of PHonon/PH/q2r.f90. *Program matdyn.x may be used to produce phonon modes and frequencies at any q using the Interatomic Force Constants file as input. Input documentation in the header of PHonon/PH/matdyn.f90.* See Example 02 for a complete calculation of phonon dispersions in AlAs. source: http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node1.html I hope it will solve your issue. Best regards, Filipe On Tue, Apr 1, 2014 at 8:49 AM, Peram sreenivasa reddy < peramsreenivas at gmail.com> wrote: > Dear xirainbow, > > Thank you very much for your replay. > > In that case.dyn1 file also it is giving same only as in the case.ph.out > file. > > Please give me more clarification. > > Thanking you. > > > > On Tue, Apr 1, 2014 at 3:15 PM, xirainbow <nkxirainbow at gmail.com> wrote: > >> You can find the answer at the end of *.dyn* files. >> >> On Mon, Mar 31, 2014 at 11:10 PM, Peram sreenivasa reddy >> <peramsreenivas at gmail.com> wrote: >> > Dear Pwscf, >> > >> > In my phonon calculations i got one imaginary mode in gamma to X >> direction. >> > I want to know which mode it is? and due to which atom it is happening? >> > >> > I checked the case.ph.out file. In this file it is given like below. >> > >> > Mode symmetry, O_h (m-3m) point group: >> > omega( 1 - 3) = -16.6 [cm-1] --> T_1u G_15 G_4- I >> > omega( 4 - 6) = 122.3 [cm-1] --> T_1u G_15 G_4- I >> > omega( 7 - 9) = 145.0 [cm-1] --> T_2g G_25' G_5+ R >> > omega( 10 - 12) = 258.5 [cm-1] --> T_1u G_15 G_4- I >> > >> > Here i am attaching the case.agr file >> > >> > Here all acoustic modes are given with same frequency. How can know that >> > particular mode name. >> > >> > >> > My system is X2YZ type. How can i know this imaginary mode is due to >> which >> > atom. I plotted partial phonon density of states also. But all atoms are >> > giving same contribution in this acoustic mode region. >> > >> > Thank you in advance. >> > >> > >> > >> > _______________________________________________ >> > Pw_forum mailing list >> > Pw_forum at pwscf.org >> > http://pwscf.org/mailman/listinfo/pw_forum >> >> >> >> -- >> ____________________________________ >> Hui Wang >> School of physics, Henan University of Science and Technology, Henan, >> China >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- _________________________________________ Filipe Camargo Dalmatti Alves Lima PhD Student University of S?o Paulo, Physics Institute, Materials Physics Department, Nanomol Group, Brazil. Phones: (11) 3091-6881 (USP) (11) 97408-2755 (Vivo) -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140401/f6b7ce75/attachment.html