Transition metals harmonic vibrational frequencies

Existing basis sets perform poorly for transition metals, the major problem being the D shell. An improved 6-3IG basis set (called m6-31G) for first-row transition metals has been proposed, with new orbital exponents and contraction coefficients for the D shell, which performs uniformly well across the entire first-row transition metal series from Sc to Cu. The quality of the new basis set is demonstrated for accurate prediction of ionization energies and bond dissociation energies, as well as structural parameters and harmonic vibrational frequencies of diatomic and polyatomic molecules. Because of its uniformly good performance for all first row transition metals, this m6-31G basis set, and its derivatives, e.g., m6-31G, is recommended over the original 6-3IG set or its derivatives. We await applications to shielding calculations. 

The Vibrational Frequencies and Harmonic Force Fields of Transition Metal Complexes... 

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