On Nov 18, 2009, at 5:48 , yuning wu wrote: > I am considering to use virtual crystal approximation to study a > system > with vacancy doped not a good idea IMHO - P. --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222