The potential curves for the X 2Π and A 2Σ+ states of NO have been determined using large Gaussian basis sets and accounting for electron correlation with the MCPF and CASSCF/multireference CI methods. The A 2Σ–X2Π electronic transition moment (γ system) is found to increase monotonically... mehr

Theoretical calculations have been performed to determine the spectroscopic constants for the ground and selected low-lying electronic states of the transition-metal noble-gas ions VAr+, FeAr+, CoAr+, CuHe+, CuAr+, and CuKr+. Analogous calculations have been performed for the ground states of the... mehr

We find the optimal structures of the homonuclear tetramers and pentamers of Cu, Ag, and Au to be planar trapezoidal. However, on the basis of spin densities deduced from electron spin resonance experiments, it has been suggested that these pentamers have distorted trigonal bipyramidal... mehr

The successive binding energies of up to four H2O and NH3 ligands to Cu+ are computed at the self-consistent-field and modified coupled-pair functional levels. The most stable structures are those where all ligands are equivalent. Replacing Cu+ by a point charge gives binding energies that are in... mehr

We describe a basis-set-expansion Dirac–Hartree–Fock program for molecules. Bond lengths and harmonic frequencies are presented for the ground states of the group IV tetrahydrides CH4, SiH4, GeH4, SnH4, and PbH4. The results are compared with relativistic effective core potential (RECP)... mehr

The alkaline earth–alkali diatomics are found to have weak bonds, because the diffuse alkali valence s orbitals cannot form a bond of sufficient strength to pay the promotion energy of the alkaline-earth atoms. This leads to van der Waals bonding in the neutrals as well as the negative ions. In... mehr

The energies for the interaction of a hydrogen atom with a nitrogen molecule have been calculated for large separation distances using a complete-active-space self-consistent-field/externally contracted configuration interaction method. H–N2 transport cross sections and collision integrals have... mehr

Potential energy curves for HeH, NeH, and ArH are determined using large basis sets and high levels of theory. The computed potential energy curves are in excellent agreement with the experimentally determined model potentials for HeH and NeH, but differ with the model potentials deduced for ArH... mehr

Ab initio calculations employing large basis sets are performed to determine an accurate potential energy surface for H–H2 interactions for a broad range of separation distances. At large distances, the spherically averaged potential determined from the calculated energies agrees well with the... mehr

The structure and energetics of the alkali and alkaline-earth monohydroxides are studied at both the self-consistent-field and singles plus doubles configuration-interaction level using Gaussian basis sets of at least triple-zeta plus double polarization quality. BeOH is found to be bent, with a... mehr