Hybrid QM/classical models: Methodological advances and new applications

Abstract

Hybrid methods that combine quantum mechanical descriptions with classical models are very popular in molecular modeling. Such a large diffusion reflects their effectiveness, which over the years has allowed the quantum mechanical description to extend its boundaries to systems of increasing size and to processes of increasing complexity. Despite this success, research in this field is still very active and a number of advances have been made recently, further extending the range of their applications. In this review, we describe such advances and discuss how hybrid methods may continue to improve in the future. The various formulations proposed so far are presented here in a coherent way to underline their common methodological aspects. At the same time, the specificities of the different classical models and of their coupling with the quantum mechanical domain are highlighted and discussed, with special attention to the computational and numerical aspects.