[Pw_forum] vacancy defect

[Phillip Nyawere]

Hello all,
I am calculating vacancy formation energy of barium flouride. I am using a
super cell of 96 atoms. When I create barium vacancy and do a relax
calculation, the vacancy energy is positive in sign. When i do the same for
flouride ion, the vacancy energy turns to be negative. This energy is
calculated by the formula E = E(vacancy) + E(single atom) - E(pure crystal).
Both energies I hope should be positive.
Thanks,
-- 
Phillip W. Otieno Nyawere,
Kabarak University,
P.O. Box Private Bag - 20157,
KABARAK
Nakuru Kenya
Tel +254728342054,
pnyawere at gmail.com, potieno at kabarak.ac.ke

God raises the meek from the ground and sits them with Kings.
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