A toolkit to assist ONIOM calculations

Abstract

A general procedure for quantum mechanics and molecular mechanics (QM/MM) studies on biochemical systems is outlined, and a collection of PERL scripts to facilitate ONIOM-type QM/MM calculations is described. This toolkit is designed to assist in the different stages of an ONIOM QM/MM study of biomolecules, including input file preparation and checking, job monitoring, production calculations, and results analysis. An iterative procedure for refitting the partial charges of QM region atoms is described and yields a more accurate treatment of the electrostatic interaction between QM and MM regions during QM/MM calculations. The toolkit fully supports this partial charge-refitting procedure. By using this toolkit for file conversions, structure manipulation, input sanity checks, parameter lookup, charge refitting, tracking optimizations, and analyzing results, QM/MM studies of large size biochemical systems can be much more convenient and practical.