Abstract
The Nobel Prize in Chemistry 2013 was awarded jointly to Martin Karplus, Michael Levitt and Arieh Warshel for the development of multiscale models for complex chemical systems. From the simplest approximation of molecular mechanics (MM) to quantum mechanics (QM), computational techniques allow simulating a great variety of
chemical systems. Combined QM/MM methodologies, however, are the best consensus for treating complex biological systems. Herein we review the theoretical basis of QM/MM methods and their applications during the last twenty years.