25 research outputs found
Polarizable Atomic Multipole Water Model for Molecular Mechanics Simulation
A new classical empirical potential is proposed for water. The model uses a polarizable atomic multipole description of electrostatic interactions. Multipoles through the quadrupole are assigned to each atomic center based on a distributed multipole analysis (DMA) derived from large basis set molecular orbital calculations on the water monomer. Polarization is treated via self-consistent induced atomic dipoles. A modified version of Thole’s interaction model is used to damp induction at short range. Repulsion-dispersion (vdW) effects are computed from a buffered 14-7 potential. In a departure from most current water potentials, we find that significant vdW parameters are necessary on hydrogen as well as oxygen. The new potential is fully flexible and has been tested versus a variety of experimental data and quantum calculations for small clusters, liquid water, and ice. Overall, excellent agreement with experimental and high level ab initio results is obtained for numerous properties, including cluster structures and energetics and bulk thermodynamic and structural measures. The parametrization scheme described here is easily extended to other molecular systems, and the resulting water potential should provide a useful explicit solvent model for organic solutes and biopolymer modeling
Recommended from our members
Description of Potential Energy Surfaces of Molecules using FFLUX Machine Learning Models
yesA new type of model, FFLUX, to describe the interaction between atoms has been
developed as an alternative to traditional force fields. FFLUX models are constructed from applying
the kriging machine learning method to the topological energy partitioning method, Interacting
Quantum Atoms (IQA). The effect of varying parameters in the construction of the FFLUX models is
analyzed, with the most dominant effects found to be the structure of the molecule and the number of
conformations used to build the model. Using these models the optimization of a variety of small
organic molecules is performed, with sub kJ mol-1 accuracy in the energy of the optimized molecules.
The FFLUX models are also evaluated in terms of their performance in describing the potential energy
surfaces (PESs) associated with specific degrees of freedoms within molecules. While the accurate
description of PESs presents greater challenges than individual minima, FFLUX models are able to
achieve errors of <2.5 kJ mol-1 across the full C-C-C-C dihedral PES of n-butane, indicating the future
possibilities of the technique