Dear all
I want to examine the lifetime of phonon at Gamma-point via the calculations of phonon-phonon interaction with use of d3.x. Recently I encountered one problem rerating on the symmetry operation of the third-order anharmonic force tensor of Si. ------------------------ (1) I calculated the tensor at q=(0,0,1) (X-point) following the strategy shown in example 14, with PWSCF ver4.1. Then, I obtained the anharmonic tensor ( see please, "si.anh_X" attached with this mail), and I confirmed it is completely the same as the one seen in reference in example 14. (2) Next, I calculated the tensor at q=(0,1,0) which point is equivalent to X-point, and anharmonic force tensor at q=(0,0,1) is obtained by symmetry operation. I expected that the tensor obtained in (1) SHOULD be equivalent to that in (2) after symmetry operation due to the equivalence in q-points. However, contrary to the expectation, a different result is observed in the anharmonic tensor at q=(0,0,1) obtained by the symmetry operation ( from q(0,1,0) to q(0,0,1)), see please, "si. anh_X_2"); actually, some components are same but considerable difference are observed. I'd like to know what is wrong in my calculation/input-files/strategy on the computation. -------------------------- I am a really beginner for use of d3.x, and may be this problem comes from a lack of my attentiveness to the calculation. I'm so sorry for disturbing your time, but If you could give me some helps, I really appreciate for your kindness. I attached some files; the input and output files that are in "files.tar.gz". I'd like to say thank you very much, in advance. Haruhiko Dekura ======================================== Haruhiko Dekura Postdoctoral Fellow Senior Research Fellow Center, Ehime University, 2?5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan ===================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110125/b5246270/attachment-0001.htm -------------- next part -------------- A non-text attachment was scrubbed... Name: files.tar.gz Type: application/x-gzip Size: 31151 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110125/b5246270/attachment-0001.bin