MOLECULAR-DYNAMICS SIMULATIONS OF AQUEOUS FORMAMIDE SOLUTION .1. STRUCTURE OF BINARY-MIXTURES

Molecular dynamics simulations have been performed for water-formamide mixtures over the whole concentration range. Structural properties of the mixture were investigated through the radial distribution functions (RDF), hydrogen bond network properties, and the statistical geometry approach. It is shown that atom-atom RDFs are not quite reliable fbr complete description of concentrational dependence of the structural changes in the mixture. On the basis of the RDF and distortion of Delaunay simplices analyses, it is concluded that formamide-like order dominates in the spacial arrangement of the mixture's structure and that the distortion of the native water structure hardly changes upon small formamide additions. H-bond analysis and dipole correlation functions show that the local geometry of the bonded molecules remains nearly unchanged with varying composition of the mixture, but that the formamide H-bond network changes dramatically upon addition of small water amounts.