[Phonopy-users] negative frequencies, cp2k interface

[Kadioglu Ö. <ozg...@ep...>]

Hello,

I am working on phonon properties of MOFs. There are some challenging structures that I constantly have negative frequencies for. I managed to decrease the number of negative frequencies by pushing the geometry optimization more and using K-points while optimizing on cp2k. However, I still had negative frequencies, then I did cell-optimization but afterwards the number of negative frequencies increased again.

I checked the previous email threads, seems like I should check the eigenvectors corresponding to the negative frequencies. I did that by using --eigvecs tag and got the eigenvectors written in mesh.yaml file. But i do not know how to move on after this point. How do we move the normal modes with negative frequencies before trying a new optimization? If you have any other suggestion for me to check I would be very glad.

Also, with the version 2.4.2, it takes much longer for the displacements to be created. It was only couple of seconds with the previous versions of phonopy, for a system consisting of 200-300 atoms, now it is 1-2 minutes to create cp2k input files with the displacements. May i ask why did it change significantly?

PS: I am using phonon --cp2k interface.

Thanks in advance.



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Özge Kadioglu

Doctoral Assistant
Laboratory of Molecular Simulation (LSMO)
École Polytechnique Fédérale de Lausanne