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The acetonitrile molecule is used as a critical test case for studying solvation effects on static and dynamic hyperpolarizabilities within the reaction field model. With due consideration of a parameter free cavity, local field factors, and inertial contributions, the hyperpolarizability of acetonitrile in solutions can be obtained, with about the same accuracy as in the gas phase.

We show that the Comment of Kirtman et al. [J. Chem. Phys. 108, 4355 (1998), preceding paper] does not explain the conspicuous fact that the low-order random phase approximation gives the best result for the hyperpolarizability of butadiene, and call for new high-level calculations to resolve the controversy.

The structure of a Lennard-Jones (LJ) fluid subjected to diverse external fields maintaining the equilibrium with the bulk LJ fluid is studied on the basis of the third-order+second-order perturbation density-functional approximation (DFA). The chosen density and potential parameters for the bulk fluid correspond to the conditions situated at "dangerous" regions of the phase diagram, i.e., near the critical temperature or close to the gas-liquid coexistence curve. The accuracy of DFA predictions is tested against the results of a grand canonical ensemble Monte Carlo simulation. It is found that the DFA theory presented in this work performs successfully for the nonuniform LJ fluid only on the condition of high accuracy of the required bulk second-order direct correlation function. The present report further indicates that the proposed perturbation DFA is efficient and suitable for both supercritical and subcritical temperatures.

A critical test of the classical nucleation theory applied to condensed phases has been carried out for the liquid miscibility gap system, methylcyclohexane‐perfluoromethylcyclohexane (C7H14–C7F14). The densities of, and the interfacial free energies between the coexisting liquid phases have been measured as a function of temperature. The interfacial free energy is found to vary as the 32 power of the critical temperature Tc, less the experimental temperature, and these data are used to calculate the gradient energy parameter κ in the Cahn‐Hilliard theory of nucleation. The magnitudes of the relevant parameters are such that the Cahn‐Hilliard theory reduces to the classical theory for the present system.These data, together with literature data on the thermodynamic properties of the bulk solutions, enable the degree of undercooling for a sensible nucleation rate to be calculated from classical theory. The experimentally determined undercoolings necessary to nucleate the C7H14‐rich phase from the solution ...