Atom-Bond Electronegativity Equalization Method Fused into Molecular Mechanics. II. A Seven-Site Fluctuating Charge and Flexible Body Water Potential Function for Liquid Water

Abstract

The ABEEM-7P model, which is a transferable, intermolecular-potential seven-points approach including fluctuating charges and flexible body, is based on the combination of the atom-bond electronegativity equalization (ABEEM) and molecular mechanics (MM). This model has been successfully explored in regard to the properties of gas-phase small water clusters in reasonable agreement with available experiments and other water models. This model is further tested by comparing the calculated energetic, structural, and dynamic properties of liquid water over a range of temperatures (260−348 K) with available experimental results and those from other water models. Molecular dynamics simulations of liquid water with ABEEM-7P were performed using the Tinker MM program. All simulations were conducted in the microcanonical NVE ensemble or canonical NVT ensemble, using 216 water molecules in a cubic simulation cell furnished with periodic boundary and minimum image conditions, and the density of the solvent was set to the experimental value for the temperature of interest. The ABEEM-7P potential gives a reasonable experimental reproduction of the intramolecular O−H bond length and H−O−H bond angle in the liquid at room temperature. The ABEEM-7P model presents the quantitative charges of O atoms, H atoms, O−H bonds, and lone-pair electrons per monomer water in the liquid and their changing in response to different ambient environment from 260 K to 348 K. Especially, ABEEM-7P applies the parameter k lp ,H(R lp ,H) to explicitly describe short-range interaction of the hydrogen bond in the hydrogen-bond interaction region. The computed ABEEM-7P properties of the liquid-phase water at room temperature, such as average dipole moment, static dielectric constant, heats of vaporization, radial distribution function, and diffusion constant, are fairly consistent with the available experimental results. The ABEEM-7P model also performs well for the temperature dependence of liquid properties: the static dielectric constant and the heats of vaporization by ABEEM-7P decrease as the temperature increases, in good agreement with the experimental values.

Theoretical Study on Co3+ in Aqueous Solution in Terms of ABEEM/MM Model

“…Very recently, we successfully used the ABEEM/MM model in simulating a correct description of the properties of pure water and monovalent ion/water systems. [27][28][29][30] The systematic study on monovalent ions in water obtained a lot of important properties, which are in good agreement with those obtained from the experimental measurements, such as radial distributions, coordination numbers, diffusion coefficients, OH bond stretching spectra, solvation energies, etc. Lately a number of articles have been devoted to EXAFS studies of hydration of 3d transition metal ions.…”

“…The recently developed seven-site flexible ABEEM-7P water model with fluctuating charges, can reproduce the good properties of water systems and monovalent ion water systems. Here, the ABEEM-7P model 27,28 assumes that water molecule is composed of seven charge centers and allowed the vibration of bond length and bond angle. The Morse potential is used to represent the O-H bond stretching, the harmonic potential is employed to represent the H-O-H angle bending, and the Lennard-Jones interaction between water molecules involves oxygen-oxygen, hydrogen-hydrogen, and oxygen-hydrogen interactions.…”

Mg2+/Ca2+ binding to DNA bases: a quantum chemical method and ABEEMσπ/MM fluctuating charge model study

“…In order to effectively describe the hydrogen bond interaction, which is quite different from the common electrostatic interactions, we introduce a new parameter k(R ij ) in the hydrogen bond interaction region [72][73][74]. k(R ij ) is dependent on the distance of metal cation and lone-pair electron, R ij , in the present study (Eq.…”

“…Meanwhile, although the QM region polarizes in response to the MM partial charges, the reverse is not also true (although fully polarizable QM/MM methods are being developed). Based on the atom-bond electronegativity equalization method (ABEEM) [69][70][71] fused into MM, Yang et al [72][73][74] have established a new generation of polarization molecular force field, that is, the ABEEMrp/MM fluctuating charge model. It has been applied successfully to the water system [72,73], ion solvation [75][76][77], organic molecules [78], peptides [79], and nucleic acid [74,75].…”

Molecular dynamics simulations of LiCl association and NaCl association in water by means of ABEEM/MM

“…In the present work, we use the constrained molecular dynamics simulations in terms of the ABEEM-7P water model [28][29][30][31] to calculate the mean force and the PMF for the LiCl and NaCl ion pairs. The present simulations differ from previous treatments in the following respects.…”