Semiempirical methods: current status and perspectives

Semiempirical methods for calculating potential surfaces are reviewed, with particular emphasis on MNDO and related methods. Topics include the rigorous derivation of semiempirical methods from first principles, the analysis of correlation effects, a comparison between semiempirical and ab initio transition states, and a survey of applications. Possible improvements for MNDO-type methods are discussed, and specific refinements are suggested.