Polyoxymethylene: The Hessian biased force field for molecular dynamics simulations

A vibrationally accurate force field (MSXX) is developed for molecular dynamics simulations of polyoxymethylene polymers (-(-OCH₂-)-). This force field is developed using the biased Hessian with singular value decomposition method (BH/SVD) applied to dimethyl ether and dimethoxymethane. The resultant force field contains parameters that are needed for molecular dynamics simulations of polyoxymethylene. Charges are derived using the electrostatic potential derived point charge calculations. The full ab initio (HF/6-31g**) torsional potential energy surface is fit using a Fourier series expansion to accommodate the "anomeric" effect in dimethoxymethane. The force field was applied to studies of tri- and tetramethoxymethane and is being applied to studies of the polymers.