A Quantum Chemical Topology Picture of Intermolecular Electrostatic Interactions and Charge Penetration Energy.

Fernando Jiménez-Grávalos,Dimas Suárez

doi:10.1021/acs.jctc.1c00263

Fernando Jiménez-Grávalos, Dimas Suárez

Open Access

https://doi.org/10.1021/acs.jctc.1c00263

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Abstract

Based on the Interacting Quantum Atoms approach, we present herein a conceptual and theoretical framework of short-range electrostatic interactions, whose accurate description is still a challenging problem in molecular modeling. For all the noncovalent complexes in the S66 database, the fragment-based and atomic decomposition of the electrostatic binding energies is performed using both the charge density of the dimers and the unrelaxed densities of the monomers. This energy decomposition together with dispersion corrections gives rise to a pairwise approximation to the total binding energy. It also provides energetic descriptors at varying distance that directly address the atomic and molecular electrostatic interactions as described by point-charge or multipole-based potentials. Additionally, we propose a consistent definition of the charge penetration energy within quantum chemical topology, which is mainly characterized in terms of the intramolecular electrostatic energy. Finally, we discuss some practical implications of our results for the design and validation of electrostatic potentials.

Highlights

Molecular mechanics (MM) simulations take advantage of simple potential energy functions to tackle large molecular systems such as those involved in biochemical processes
We considered on the one hand two widely-used electrostatic potentials: the AMOEBA potential based on the distributed multipole analysis (DMA) method[35] up to the quadrupoles, and the Coulombic potential evaluated with the restrained electrostatic potential (RESP) atomic charges as those used in the General Amber Force Field (GAFF) force field
In this work we have made extensive use of the atomic and molecular descriptors defined by the interacting quantum atoms (IQA)/IQF energy decomposition method in order to characterize the electrostatic contributions to the formation energy of selected non-covalent complexes relevant to biomolecular systems

Summary

Introduction

Molecular mechanics (MM) simulations take advantage of simple potential energy functions to tackle large molecular systems such as those involved in biochemical processes. These MM potentials, which are named as force fields (FFs), are built upon certain physical models that lead to energy functions representing atomic or fragment contributions that provide a reliable global description with affordable computational requirements and depend on a set of parameters, which are commonly fitted to reference experimental and/or quantum mechanical (QM) data.[1]. Probably one of the most appealing attributes of MM methods, is their transferability, the ability to correctly describe the set of model molecules/fragments, and other different systems provided they are built upon similar chemical units

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