Fermi resonance in CO2: Mode assignment and quantum nuclear effects from first principles molecular dynamics

• DOI: 10.1063/1.4979199
• Publication Date: 2017-04-03T13:36:07Z
• Authors: Marie Basire; Félix Mouhat; Guillaume Fraux; Amélie Bordage; Jean-Louis Hazemann; Marion Louvel; Riccardo Spezia; Sara Bonella; Rodolphe Vuilleumier
• Keywords: Fermi resonance

Vibrational spectroscopy is a fundamental tool to investigate local atomic arrangements and the effect of environment, provided that spectral features can be correctly assigned. This challenging in experiments simulations when double peaks are present because they have different origins. Fermi dyads common class such doublets, stemming from resonance excitation mode with overtone another. We new, efficient approach unambiguously characterize resonances density functional theory (DFT) based condensed phase systems. With it, assigned two resonating modes identified. also show how data DFT employing classical nuclear dynamics post-processed combined perturbative quantum treatment at finite temperature include analytically thermal effects. The inclusion these effects crucial correct some qualitative failures Newtonian low as, particular, behavior frequency splitting dyad. show, by comparing experimental for paradigmatic case supercritical CO2, substantial even ambient conditions our scheme provides an accurate computationally convenient account them.