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Using the Stepanov approximation, computer calculations have been made of the effect of deuterium substitution on the length of the hydrogen bond. Expansion on replacement with deuterium is a feature of both symmetric and asymmetric double-minimum potentials, contraction of single-minimum potentials. The origin of the effect and its relation to observations is discussed.

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The charge-induced dipole induction energy and the dipole–dipole dispersion energy for the ground state H–H+ and H–H interactions are used as model energies for investigating the feasibility of using Gaussian basis functions to calculate long-range intermolecular forces. The use of various types of Gaussian basis sets to represent the first-order wavefunction, Ψ(1), in the calculation of the interaction energies and the errors introduced into the calculations by using Gaussian representations of the exact zeroth-order wavefunctions for the isolated atoms are considered. Satisfactory long-range forces, at least for the simple interactions considered here, can be obtained by using small Gaussian basis sets to represent the interaction, that is Ψ(1), and/or the zeroth-order wavefunction.

AbstractsA one center method, based on the work of Karplus and Kolker, is discussed and used to calculate the induction energy, through O(W8), for the H ( 1s) -H+ interaction employing two types of Gaussian basis sets constructed from functions of the form {rie--ar2}. The effective hydrogen atom excitation energies and transition multipole moment matrix elements generated in these calculations are used to calculate the dispersion energy for the H( 1s) -, and the R9 triple dipole energy corresponding to the interaction of three H( 1s) atoms. The results indicate that Gaussian functions can form good basis sets for obtaining long range forces for a variety of multipole interaction energies.