Hello. Is the FOCK matrix that is printed out from Gaussian 94 from F'C'=eC' or is it from: FC = eSC? The molecular orbital coefficients must be C (not C') with eigenvalues e. Thank you. Iraj. -- Iraj Daizadeh Department of Chemistry University of California One Shields Ave. Davis, CA 95616-5295 Phone: 530.754.8695 Fax: 530.752.8995 email: daizadeh #*at*# kappa.ucdavis.edu