A transferable H2O interaction potential based on a single center multipole expansion: SCME

Abstract

Abstract. A transferable potential energy function for describing the interaction between water molecules is presented. The electrostatic interaction is described rigorously using a multipole expansion. Only one expansion center is used per molecule to avoid the introduction of monopoles. This single center approach turns out to converge and give close agreement with ab initio calculations when carried out up to and including the hexadecapole. Both dipole and quadrupole polarizability is included. All parameters in the electrostatic interaction as well as the dispersion interaction are taken from ab initio calculations or experimental measurements of a single water molecule. The repulsive part of the interaction is parametrized to fit ab initio calculations of small water clusters and experimental measurements of ice I h . The parametrized potential function was then used to simulate liquid water and the results agree well with experiment, even better than simulations using some of the point charge potentials fitted to liquid water. The evaluation of the new interaction potential for condensed phases is fast because point charges are not present and the interaction can, to a good approximation, be truncated at a finite range.

Modeling Molecular Interactions in Water: From Pairwise to Many-Body Potential Energy Functions

“…(a) Logarithmic-scale errors in SCME 213 two-body absolute energies relative to CCSD(T)/CBS reference data reported in ref 191. (b) Correlation plot between SCME ( y axis) and CCSD(T)/CBS ( x axis) three-body energies calculated for the set of trimer geometries reported in ref 144.…”

Long-Time-Scale Simulations of H2O Admolecule Diffusion on Ice Ih(0001) Surfaces

“…The simulations presented here made use of a simple, point charge model fitted to bulk properties, so its applicability to surface properties can be questioned. Further work, using a more accurate description, such as the single center multipole expansion (SCME) potential 34 would be desirable. The SCME potential gives better agreement with the experimental lattice constants and cohesive energy of ice Ih than the potential function used here.…”

Transient Changes in Molecular Geometries and How to Model Them

“…This is an issue which we hope to improve upon in the future, through employing polarisable force fields, which improves on the classical modelling of partial charges. For a brief outlook on how to achieve such improvements, we respectfully break the unwritten rule of not presenting new information in final sections 1 , to show the very first steps towards incorporating a polarisable force field for water [191]. The steps were taken during a one-month visit at the University of Iceland, and are visualised by the reproduction of the potential energy curve of the water dimer.…”