How Accurate Can a Force Field Become? A Polarizable Multipole Model Combined with Fragment-wise Quantum-Mechanical Calculations

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Abstract

A new method to accurately estimate the interaction energy between a large molecule and a smaller ligand
is presented. The method approximates the electrostatic and induction contributions classically by multipole
and polarizability expansions, but uses explicit quantum-mechanical fragment calculations for the remaining
(nonclassical) contributions, mainly dispersion and exchange repulsion. Thus, it represents a limit of how
accurate a force field can ever become for interaction energies if pairwise additivity of the nonclassical term
is assumed (e.g., all general-purpose force fields). The accuracy is tested by considering protein-ligand model
systems for which the true MP2/6-31G* interaction energies can be computed. The method is shown to be
more accurate than related fragmentation approaches. The remaining error (2-5 and ∼10 kJ/mol for neutral and charged ligands, respectively) can be decreased by including the polarizing effect from surrounding fragments in the quantum-mechanical calculations.
Original languageEnglish
Pages (from-to)617-627
JournalJournal of physical chemistry. A
Volume113
Issue number3
DOIs
Publication statusPublished - 2009

Bibliographical note

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)

Subject classification (UKÄ)

  • Theoretical Chemistry

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