A new intermolecular polarizable potential for cis-formic acid. Introduction of many-body interactions in condensed phases

An HCOOH-HCOOH intermolecular potential that includes many-body effects int ended for computations of large clusters of formic acid and simulations in the liquid phase was constructed from monomer properties and ab initio calc ulations. The potential accurately predicts the minimum energies of the dim er. Predictions are also given and compared with ab initio calculations for formic acid trimer and tetramer. The results suggest that the lowest-energ y structure in large clusters consists of a cycle formed via hydrogen bonds that folds as two parallel chains linked at one end. Simulated results sug gest a liquid phase consisting of small molecular chains. Most likely, omis sion of induction effects will to results in a less structured liquid. (C) 1999 Elsevier Science B.V. All rights reserved.