Chapter

Solvation Effects on Molecules and Biomolecules

Volume 6 of the series Challenges and Advances in Computational Chemistry and Physics pp 39-102

Date:

The Discrete Reaction Field approach for calculating solvent effects

  • Piet Th. Van DuijnenAffiliated withZernike Institute for Advanced Materials, Rijksuniversiteit Groningen Email author 
  • , Marcel SwartAffiliated withInstitució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain and Institut de Química Computacional, Universitat de Girona
  • , Lasse JensenAffiliated withDepartment of Chemistry, The Pennsylvania State University

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Abstract

We present here the discrete reaction field (DRF) approach, which is an accurate and efficient model for studying solvent effects on spectra, chemical reactions, solute properties, etc. The DRF approach uses a polarizable force field, which is (apart from the short-range repulsion) based entirely on second-order perturbation theory, and therefore ensures the correct analytical form of model potentials. The individual interaction components are modeled independently from each other, in a rigorous and straightforward way. The required force field parameters result as much as possible from quantum-chemical calculations and on monomer properties, thereby avoiding undesired fitting of these parameters to empirical data.

Because the physical description is correct and consistent, the method allows for arbitrary division of a system into different subsystems, which may be described either on the quantum-mechanical (QM) or the molecular mechanics (MM) level, without significant loss of accuracy. This allows for performing fully MM molecular simulations (Monte Carlo, molecular dynamics), which can subsequently be followed by performing QM/MM calculations on a selected number of representative snapshots from these simulations. These QM/MM calculations then give directly the solvent effects on emission or absorption spectra, molecular properties, organic reactions, etc