An ab initio polarizable intermolecular potential for dimethyl ether: application to liquid simulations

An intermolecular potential for dimethyl ether derived from properties of the monomer and ab initio calculations on the dimer based on an intermolecular perturbation theory is proposed. The interaction energy provided by the potential is a combination of contributions with specific physical significance. The potential was constructed in such a way as to explicitly consider many-body effects, which can be significant in condensed phases. The dimer energies and geometries for the gas phase provided by the potential are quite consistent with the ab initio results. The dispersive term plays a prominent role in most of the minima identified, the electrostatic contribution prevailing only in a single configuration. The results for the trimer reflect a delicate equilibrium between different types of interaction where the dispersive and electrostatic terms prevail in any case. The simulated results for the condensed phase are satisfactorily consistent with both their experimental counterparts and those derived from empirical potentials. In the liquid phase, dimethyl ether molecules cluster in dimers. These occur preferentially in a conformation where the two molecules lie in an antiparallel arrangement in the same plane. The first coordination sphere comprises 13 molecules. (C) 2000 Published by Elsevier Science B.V.