Molecular dynamic simulations of a liquid formamide and N,N-dimethylformamide with new quantum mechanical potential

Molecular dynamics simulations with new reliable quantum chemical potential have been performed for liquid N,N-dimethylformamide (DMFA). Structural properties of DMFA were investigated in comparison with earlier results for liquid formamide (FA) using the atom-atom radial distribution functions, dipole-dipole correlation function, H-bonds network properties and statistical geometry approach. Autocorrelation functions were applied to study the translational/reorientational diffusion and librational/vibrational molecular motion. Liquid FA structure can be described as a continuous rambling H-bond network with great variety of individual H-bond geometry. Stacked and linear dimeric formations arise in the DMF A local structure due to predominance of dipole - dipole interactions. Similar modes of vibrational molecular motions are observed for FA and DMFA. Librational molecular motions have the same time scale for FA and DMFA, but rotational motions are slightly anisotropic for FA. (C) 2003 Elsevier Science B.V. All rights reserved.