Vibrational analysis beyond the harmonicity from Ab initio molecular dynamics: Case of cytosine in its anhydrous and aqueous forms

Abstract

AbstractThis study provides the set of theoretical anharmonic fundamental transitions for cytosine in its anhydrous and hydrated forms from a vibrational analysis issuing from a time‐dependent approach. This evaluation is compared to the time‐independent VPT2 approach and to the experimental data available in the literature for the two forms. To investigate the vibrational property of a solute in a polar protic solvent, that is, the aqueous form of cytosine in this particular case, a practicable computational strategy to properly take into account the solvent effect is proposed. This is done by considering a combination of polarizable continuum model and of discrete solvent molecules model. The number of solvent molecules was chosen in such a way that the solute–solvent complex presents only one dominant stable conformer at 298 K. The quality of this combined solvent model is illustrated by comparing the structural and anharmonic vibrational properties achieved with those obtained from a purely implicit and purely explicit solvent model. © 2012 Wiley Periodicals, Inc. Int J Quantum Chem, 2012