THEORETICAL VIBRATIONAL ENERGIES OF [CRO4]2-, [MNO4]2- AND [FEO4]2-

Density functional theory (DFT) calculations of the vibrational energi es of the tetrahedral complexes [MO4]2- (M = Cr, Mn, Fe) are reported using both local and non-local functionals. The computed results vary slight with choice of basis set but are less sensitive to the choice o f functional. The computed data tend to be slightly too large for the high-energy stretching modes and slightly too small for the low-energy bending/torsion modes. The average deviation between theory and exper iment is about 4%, with a maximum average error of only 7% depending o n which experimental data are used in the comparison.