A force field for simulations of 1,2-dimethoxyethane and poly(oxyethylene) based upon ab initio electronic structure calculations on model molecules

Abstract

The force field parameters for simulations of 1,2-dimethoxyethane (DME) and poly(oxyethylene) were determined mainly utilizing the geometries and energies of the conformational minima and low-lying barriers in DME and diethyl ether (DEE) as determined from ab initio electronic structure calculations. A set of partial atomic charges, used to describe electrostatic interactions, was parameterized based upon the dipole moment and the partial atomic charges for DEE as determined from ab initio electronic structure calculations. The force field parameters thus determined reproduce well the experimental second virial coefficients of gas-phase DEE vs temperature. Furthermore, a stochastic dynamics simulation of DME based on our force field leads to an electron diffraction radial distribution function in good agreement with experiment. Detailed comparison of the electron diffraction radial distribution function as a function of conformer distribution with experiment corroborates the previous finding of Astrup that the order of conformer populations in DME is tg±g∓ > tgt > ttt. © 1993 American Chemical Society.