[Pw_forum] on optimize amorphous structure

[li niu]

Dear Jean-Yves Raty,
  
Thanks for your help!
I don't know if I express myself clearly. I use a model structure, generated by CPMD. This model contains 64 atoms in a periodically repeated cubic cell, at the experimental density. The electric structure and optical properties have been previously calculated for the same model structure.
   I want to calculate vibrational properties for the same structure. In this case, need I optimize this structure ? If the answer is yes, do I use the relax, vc-relax or others?
   
  Thanks!
  
Best!
   
  Niu Li

       
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