DENSITY-FUNCTIONAL PSEUDOPOTENTIAL STUDIES OF MOLECULAR GEOMETRIES, VIBRATIONS, AND BINDING-ENERGIES

This paper presents density functional calculations of structural and electronic properties of molecules by the use of ab initio pseudopotentials and the linear combination of Gaussian-type orbitals optimized by simulated annealing. A comprehensive study was carried out for various molecules whose constituent atoms cover a major portion of the Periodic Table from H to Po except for atoms in the lanthanum group. Bond distances, vibrational frequencies, and binding energies are obtained and compared with available experimental results and all-electron calculations. We find that, in general, pseudopotential bond distances are within 0.1 angstrom of experimental and all-electron results, and relative uncertainties of vibrational frequencies are, on the average, less than 12%. For binding energies, pseudopotential results agree well with corresponding all-electron results. For most cases, nonlocal gradient corrections to the local density approximation significantly improve both pseudopotential and all-electron binding energies.