Calculation of the Resonance Raman Intensities of Nickel bis-Dimethylglyoxime by means of Density Functional Theory and the Transform Theory

Abstract

The resonance Raman (RR) spectra of nickel bis-dimetliylglyoxime (NiDMG) were calculated in the framework of the transform theory of RR scattering by means of the Rush and Peticolas approximation in combination with density functional theory (DFT). The 1¹Bu and 1¹Au excited state geometries, required by this approach, were optimised within time-dependent DFT at the B3LYP and B3P86 levels of theory, using a Newton-Raphson algorithm where the first and second derivatives of the molecular excited state energies were calculated numerically through finite difference approximations. The B3LYP ground state force field was scaled with a set of global scaling factors that correct for errors arising from the quantum chemical method and the harmonic approximation. Comparison between the experimental RR spectra of NiDMG obtained with 413 nm excitation and those calculated in resonance with the transitions to the 1¹Bu and 1¹Au states show a good agreement for the most intense RR bands.