The characteristics of Raman spectra calculations of solvated molecular structures were investigated. Cysteamine hydrochloride solution in water was chosen as the model system. The calculations were performed using an implicit solvation model Integral Equation Formalism Polarizable Continuum Model (IEFPCM) with explicit solvent molecules added to the structure model. Geometry optimization of such structures might be time consuming due to a flat energy surface. The analysis of alternation of the calculated Raman spectra during the geometry optimization process revealed that a considerably lower number of optimization steps was necessary to get semi-accurate results. We have found that 10–15 optimization steps are enough for such models, and calculation errors for such models do not exceed 5–10%. The correlations between the calculation errors and internal forces on atoms or changes of the geometric parameters of the models are observed.

Keywords: Raman spectra, geometry optimization, solvation, DFT, cysteamine