KOHN-SHAM CALCULATIONS ON OPEN-SHELL DIATOMIC-MOLECULES

We report density functional theory calculations of bond-lengths, frequencies and dissociation energies for a number of open-shell diatomic molecules. Our calculations were performed with very accurate quadrature for three distinct forms of the exchange-correlation functional: S-VWN, B-P86-VWN and B-LYP. We find good agreement between experiment and theory for equilibrium bond lengths and harmonic frequencies. The density functional theory methods represent a significant improvement in cost and accuracy over the restricted and unrestricted Moller-Plesset techniques. We compare the relative performance of the different functionals and conclude that the gradient corrected functionals give significantly better frequencies and dissociation energies than the local density approximation (S-VWN). Kohn-Sham density functional theory calculations were performed in both the unrestricted Kohn-Sham and restricted Kohn-Sham formalisms.