I have a long-standing question that I hope you can help me with. In phonon calculations within QE, we obtain vibration frequencies and eigenvectors from the matdyn.out file.
I am particularly interested in understanding how to interpret the vibration modes. For example,
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freq ( 1) = -0.000001 [THz] = -0.000020 [cm-1]
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
( 0.010966 0.000000 -0.007875 0.000000 0.408025 0.000000 )
(0.010966, -0.007876, 0) represents the vibration displacement of the first atom or the normalized coordinates? Are the units in atomic units? For orthogonal cells, can these numbers be directly converted to atomic displacements, but how to convert for non-orthogonal cells? How should the imaginary part be understood? Thank you very much for your help.
zhouchao
Birinci değer atomun yerdeğiştirme, ikinci değer frekans, üçüncü değer aradaki mesafe. Her atom kendi biriminde olduğu için birimler atom biriminde. Değerler sadece mesafeyi belirtmediği için atomik yer değiştirmelere dönüştürülemez. Sanal kısmın değerleri negatiftir.
Dear Şükrü Aktaş,
Thank you very much for your response. I have attempted to translate and understand your answer, which suggests that atomic displacements cannot be directly read. However, I am aware that it is possible to visualize the vibrational modes using the matdyn.out file at https://interactivephonon.materialscloud.io/. Could you please advise further on this? Şükrü Aktaş
I appreciate your help and look forward to your guidance.
Best regards,
zhouchao
Atomun ilk hareketinde size verilen cevap doğrudur. Ancak atom bütün özelliklerini kaybedip sadece titreşim hareketi yaptığında heryerde özdeş atomların bütün özellikleri aynı olur.
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