[Pw_forum] Atom Mass in vc-relax or relaxation

[Yukihiro Okuno]

Dear PW Users.

I want to optimize the lattice parameter and internal atomic position, so I choose 
vc-relax calculation.

In the relaxation , can I change atomic mass arbitrary instead of true atom mass? 
In the test calculation, I had changed the mass of the system and get almost same 
lattice parameter and atomic internal position.

Does not relative relation of crystal coordinate of atoms depend on their mass ? 

And if some atoms have heavy mass and does not move, and then they cause the difficulties of conversence, 
is it one way to set same masses for all atoms to improve the conversence? 

Sincerely, 

Yukihiro Okuno.

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Yukihiro Okuno  okunoyukihiro2000 at yahoo.co.jp