A density functional study of Sc2 and Sc3

Density functional theory, using a gradient-corrected exchange-correlation functional, has been applied to determine the equilibrium properties of various spin states of the Sc2 and Sc3 molecules. The ground state of Sc2 is predicted to be 5Σu− with Re = 2.64 Å, we = 222 cm−1 and De = 0.92 eV, followed by the 3Σu− and 1Σg+ states. The equilibrium structure of the 2A1′ ground state of Sc3 is found to have D3h symmetry with a bond length of 2.83 Å. The calculated harmonic frequencies are 272 cm−1 (a1′) and 153 cm−1 (e′), while the atomization energy is 2.49 eV. Several low-lying excited states of Sc3 are found to lie about 0.2 eV above the ground state. The predicted ground states of Sc2 and Sc3 and their vibrational frequencies are in accordance with the findings of ESR and resonance Raman studies.