[Pw_forum] Can we obtain anharmonic vibration energy from s3.x?

[GAO Zhe]

Dear QE developer and users:
I am using ph.x and QHA to calculate thermodynamics properties of some compositions and their solid-solutions. However, for some materials and their solid-solution, the results shows agaist to the thermodynamics "general sense", for example, DeltaG,Delta Gibbs Free Energy, lower than ideal solution at low temperature but higher at high temperature. But in "general sense", the ideal solution line cannot be overcome, that means if one solution's DeltaG was once lower than ideal solution's, then ideal solution line should be its limitation even at very high temperature.
Therefore, I want to check whether this phenomenon was due to anharmonic effect or not. I have known that we can calculate anharmonic dynamic matrix for specified q-point by s3.x code, but I also want to know whether we can gather the anharmonic dynamic matrics to form IFC and anharmonic-phDOS. Moreover, if we can obtain IFC and phDOS for anharmonic case, is it possible to calculate Fvib from them?
Thanks.


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GAO Zhe
CMC Lab, MSE, SNU, Seoul, S.Korea
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