Is it possible to study nitrogen vacancies in GULP. Because I get an error symmetry atom not found in deftmat when I do this.Kindly let me know on the same
Whether you can study something or not depends on the limitations of the force field you are using. In principle there is no reason you can’t study a N defect if the model is correct. The error message here is more pointing to a problem with your input file though. Without seeing the input it’s not possible to say what’s wrong though.