Vibrational corrections to electric properties of relativistic molecules: The coinage metal hydrides

The dipole moment, parallel dipole polarizability, and the parallel first h yperpolarizability of the coinage metal hydrides (CuH, AgH, AuH) are studie d in the context of their vibrational contributions. The partition of the p roperty values into pure electronic, vibrational averaging, and pure vibrat ional terms is discussed, and the corresponding contributions are calculate d by means of the field-dependent Numerov-Cooley integration technique. The potential energy and property surfaces, required for the evaluation of the se contributions, follow from different high-level electronic structure cal culations. Parallel to the nonrelativistic studies, a relativistic treatmen t of the investigated properties has been carried out. It has been found th at relativistic effects significantly reduce the magnitude of the vibration al corrections to the studied properties. A particularly large relativistic reduction has been found for the vibrational contribution to the first hyp erpolatizability. The relativistic effect is enhanced with increasing nucle ar charge of the heavy atom, and can be interpreted in terms of the relativ istic effect on the potential energy and electric property curves. (C) 2001 American Institute of Physics.