Dear all Recently, I am trying to performed a DFPT calculation to get the phonon of silicene using PWSCF. Actually, i can obtain reasonable phonon dispersion of silicene using q-points up to 6x6x1 (including 4x4x1) but a negative frequency always appear in the phonon calculations with q-points of 8x8x1, 9x9x1, 12x12x1. I have tested a lot of parameter in the calculations including the k-points in scf calculations with (24x24x1) and also (32x32x1), conv_thr (1d-10,1d-12) and also tr2_ph( 1.0d-18,1.0d-20,1.0d-22). And I also tested the different potential (including Si.pbe-n-van.UPF, Si.pbe-rrkj.UPF, Si.pz-vbc.UPF) and the scheme using in relaxed the structure (i.e vc-relax directly and atomic relaxation with different lattice parameters). Unfortunately, I can only get the reasonable phonon dispersion with q-mesh below 6x6x1. In my opinion, the phonon should be converged with q-mesh. More q-mesh one used more reliable phonon one can obtain. The main test input and output files are enclosed. Could you help me check them and tell me what i missed in the calculation? Any suggestion will be appreciated!
Thanks and best wishes. Wei-Bing Zhang -- ---------------------------------------------------------------------- Dr. Wei-Bing Zhang School of Physics and Electronic Sciences Changsha University of Science and Technology, Changsha, People?s Republic of China Phone : +86 186 73108538 E-mail: zwb256 at hotmail.com, weibingzhangavh at gmail.com ---------------------------------------------------------------------- -------------- next part -------------- A non-text attachment was scrubbed... Name: 661.eps Type: application/postscript Size: 20499 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130131/2bdf014b/attachment-0002.eps -------------- next part -------------- A non-text attachment was scrubbed... Name: 991.eps Type: application/postscript Size: 20434 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130131/2bdf014b/attachment-0003.eps -------------- next part -------------- A non-text attachment was scrubbed... Name: ph.in Type: application/octet-stream Size: 161 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130131/2bdf014b/attachment-0002.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: scf.in Type: application/octet-stream Size: 1621 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130131/2bdf014b/attachment-0003.obj
