Suppose if we want to know the defect formation energy of a single nitrogen vacancy, when I specify "vacancy N " in GULP. The output says only one defect has been created.
But how can I take it confidently that only one nitrogen vacancy is being created ?
I want to study the defect formation energy in the presence of one vacancy only. How can I know that specifying as “vacancy N” for say, calcium nitride ensures only one nitrogen vacancy is created though the output says 1 defect has been created ?