Effective Time-Independent Calculations of Vibrational Resonance Raman Spectra of Isolated and Solvated Molecules Including Duschinsky and Herzberg-Teller Effects

We present a method of modeling vibrational resonance Raman scattering (RRS) spectra of isolated and solvated systems with the inclusion of FranckCondon (FC) and HerzbergTeller (HT) effects and a full account for possible differences between the harmonic potential energy surfaces of the initial and resonant electronic states. It describes fundamentals, overtones, and combination bands and computes the RRS spectrum as a two-dimensional function of the incident and scattered frequencies. The theoretical foundations of the method are described and the differences with other currently available methodologies are outlined. Applications to the phenoxyl radical in the gas phase and indolinedimethine malononitrile (IDMN) in acetonitrile and cyclohexane solution are reported, as well as comparisons with available experimental data

Investigation of the resonance Raman spectra and excitation profiles of a monometallic ruthenium(II) [Ru(bpy)2(HAT)]2+ complex by time-dependent density functional theory.

The resonance Raman (RR) properties of the [Ru(bpy)(2)(HAT)](2+) (where bpy = 2,2'-bipyridine and HAT = 1,4,5,8,9,12-hexaazatriphenylene) complex have been investigated by means of time-dependent density functional theory calculations employing the hybrid B3LYP-35 XC functional and by including the effects of the solvent within the polarizable continuum model approach. Analysis of the electronic excited-state energies has demonstrated that mainly four different metal-to-ligand charge-transfer excitations contribute to the first absorption band in vacuo and water. The simulation of the absorption spectra by including the vibronic structure of the states has shown a general agreement with the experimental spectrum recorded in water. Furthermore, significant variations of the excited-state energies and compositions have been found when the effects of the solvent are included. Calculation of the short-time-approximation RR spectra has provided the vibrational signature of each contributing state and has shown that considering only one excited state is not sufficient to accurately simulate the RR spectra for excitation frequencies in resonance with the first absorption band. A comparison of the RR spectra calculated using the vibronic theory for different excitation wavelengths with the measured spectra at 514 and 458 nm has demonstrated that inclusion of the solvent effects in the simulation scheme leads to substantial improvements of the RR intensity patterns, which allow assignment of the vibrational bands. In particular, the calculations are able to reproduce the variations of the HAT and bpy RR intensities as illustrated by their RR excitation profiles, highlighting the strong dependence of the RR intensities with respect to the excitation frequency.Journal Articleinfo:eu-repo/semantics/publishe