LAUSR

Molecular dynamics simulations of the liquid–vapor interface of water–formamide mixtures of different compositions, spanning the entire composition range, have been performed in the canonical (N, V, T) ensemble at 300 K. The layer of the surface molecules has been identified and analyzed in detail in terms of the intrinsic identification of the truly interfacial molecules (ITIM) method. The obtained results reveal the strong lateral hydrogen-bonding ability of the surface molecules in these systems. Thus, the surface molecules form a percolating lateral hydrogen-bonding network in every case, which makes the surface layer noticeably more compact than the subsequent subsurface molecular layers. However, the molecules mix with each other even on the molecular scale. Neither strong adsorption, nor lateral self-association of any of the components in the surface layer has been observed, although formamide exhibits a slight ability of being accumulated in the surface layer. Further, in contrast with the aforem...