Zusammenfassung
Recent methodological developments in our group include the extension of the semiempirical MNDO formalism to d orbitals, an approach to go beyond the MNDO model by incorporating additional one-electron terms (one- and two-center orthogonalization corrections, penetration integrals, effective core potentials), and the combination of quantum mechanical and molecular mechanical methods in QM/MM hybrid schemes. The theory and parametrization of these approaches, the statistical evaluation of the results, and selected applications are discussed, as well as an efficient implementation of analytic first and second derivatives in MNDO-type methods.