DIELECTRIC-CONSTANTS OF LIQUID FORMAMIDE, N-METHYLFORMAMIDE AND DIMETHYLFORMAMIDE VIA MOLECULAR ORNSTEIN-ZERNIKE THEORY

Kirkwood factors, yielding dielectric constants, are calculated from p air correlation functions, which are numerical solutions of the hypern etted-chain approximation of molecular Ornstein-Zernike (MOZ) theory. The combined influence of the molecular polarizability and the hydroge n bond strength is investigated. Using a reasonable diameter for the h ydrogen size in the amide group, the MOZ Kirkwood factors and dielectr ic constants are in good agreement with the experimental values. This is explained by the statistical correlations between the orientations of two near molecules, This is consistent with hydrogen bonds, forming networks in formamide and chains in N-methylformamide. (C) 1997 Elsev ier Science B.V.