A critical appraisal of the zero-multipole method: Structural, thermodynamic, dielectric, and dynamical properties of a water system.

Han Wang,Ikuo Fukuda,Haruki Nakamura

doi:10.1063/1.4943956

Han Wang, Ikuo Fukuda + Show 1 more

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https://doi.org/10.1063/1.4943956

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Abstract

We performed extensive and strict tests for the reliability of the zero-multipole (summation) method (ZMM), which is a method for estimating the electrostatic interactions among charged particles in a classical physical system, by investigating a set of various physical quantities. This set covers a broad range of water properties, including the thermodynamic properties (pressure, excess chemical potential, constant volume/pressure heat capacity, isothermal compressibility, and thermal expansion coefficient), dielectric properties (dielectric constant and Kirkwood-G factor), dynamical properties (diffusion constant and viscosity), and the structural property (radial distribution function). We selected a bulk water system, the most important solvent, and applied the widely used TIP3P model to this test. In result, the ZMM works well for almost all cases, compared with the smooth particle mesh Ewald (SPME) method that was carefully optimized. In particular, at cut-off radius of 1.2 nm, the recommended choices of ZMM parameters for the TIP3P system are α ≤ 1 nm(-1) for the splitting parameter and l = 2 or l = 3 for the order of the multipole moment. We discussed the origin of the deviations of the ZMM and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and SPME, while the magnitude of the density deviations is very small.

Highlights

We discussed the origin of the deviations of the zero-multipole (summation) method (ZMM) and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and smooth particle mesh Ewald (SPME), while the magnitude of the density deviations is very small
In a molecular simulation of a target physical system using molecular dynamics (MD) or Monte Carlo (MC) calculation, the estimation of the electrostatic interactions among charged particles in the system is critical, since the electrostatic interactions govern a variety of features of the system, including physical properties, chemical reactions, and biological functions
III, we demonstrate physical-chemical quantities employed in the investigation of the accuracy of the ZMM and give the details of the simulation protocols to conduct the strict test using a bulk water system

Summary

Introduction

In a molecular simulation of a target physical system using molecular dynamics (MD) or Monte Carlo (MC) calculation, the estimation of the electrostatic interactions among charged particles in the system is critical, since the electrostatic interactions govern a variety of features of the system, including physical properties, chemical reactions, and biological functions. In classical simulations, this should be due to the following specific features of the Coulombic electrostatic interaction. The critical issue to the short-range treatment is to improve its accuracy and remove the possible artifacts arising in it.

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