Density functional pseudopotential studies of molecular geometries, vibrations, and binding energies

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Abstract
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 Å 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.