Dear Zhou Bo: Please add your affiliation when you post email next time.
> Q1: Does pwscf have tools to calculate internal energe, specific heat, > entropy? Though I find fqha.x. Should I modify it to calculate the > other properties myself? > > Yes for internal energy. No for specific heat, entropy at present. As I know fqha.x has bug until version 4.0.5. (Maybe fixed at version 4.1, you should check it by yourself). We modified matdyn.f90 to calculate thermal properties as we need. I think it is not so difficult if you know how to do numerical integration. Alternatively, you can try qha package provided by Eyvaz Isaev. Download at https://qe-forge.org/projects/qha/ > Q2: I have a system with soft mode (negative phonon freq) in phonon > dispersion. Is it meaningful to calculate these thermal properties. If > it still have physical meaning, how to deal with the DOS below zero, > abandon it or just add into the integration? > If you don't provide us what your system is, we can not answer negative frequency is meaningful or not. Generally, negative frequency has two reasons: numerical errors or unstable structure at your calculated condition. For the former case, the negative value should not far from zero, and you can add acoustic sum rule (asr=.crystal.) to eliminate it. For the latter case, negative frequency is meaningful. It shows the structure you calculated is unstable at some direction. You should analyze this 'soft mode' carefully. For both cases, when you do integration, I THINK negative value should be abandoned. > Q3: Using matdyn.x to get the full phonon dispersion, there are some > discontiguous in phonon bands. Is there a convenient way to get > continual phonon dispersion? > Calculate different path once a time, then connect them together when you plot. Or modify the matdyn.f90 to meet your need as I did. See matdyn2.f90 at attachment. The original qpoint list in matdyn input file is replaced by connected qpoint list of qpath. More details and sample input see HowTo.pdf. Example output graph as pdc-pdos.eps. Because the attachment size in this mailing list can not exceed 200 KB. So if you want other files, send me a personal email for request. Cheers, Kun Yin School of Earth Sciences and Engineering Nanjing University China email: kyin.cn at gmail.com -------------- next part -------------- A non-text attachment was scrubbed... Name: matdyn2.f90 Type: text/x-fortran Size: 67333 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20090809/947fc64f/attachment-0001.bin
