[Pw_forum] "relax" vs. "vc-relax" calculation

[Tram Bui]

Dear Everyone,
     I have a quick question regarding the "relax" vs. "vc-relax"
calculation for my SiC structure. As I run the " scf" calculation with a
single defect, e.g. interstitial or sustitutional, the lattice parameter of
the unit cell is expected to be stretched. And as I checked, the lattice
constant got larger when introduced defect. Now, I'm just wondering between
the "relax" calculation (which will only relax the atomic position ) and the
"vc-relax" one (which will relax both atomic position and the lattice of the
unit cell), which one would you recommend to use?

Thank you very much,

Tram Bui

M.S. Materials Science & Engineering
trambui at u.boisestate.edu
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