title: Significant Contributions of the Albrecht's A Term to Nonresonant Raman Scattering Processes.
abstract: The Raman intensity can be well described by the famous Albrecht's Raman theory that consists of A and B terms. It is well-known that the contribution from Albrecht's A term can be neglected without any loss of accuracy for far-off resonant Raman scattering processes. However, as demonstrated in this study, we have found that this widely accepted long-standing assumption fails drastically for totally symmetric vibration modes of molecules in general off-resonant Raman scattering. Perturbed first-principles calculations for water molecule show that strong constructive interference between the A and B terms occurs for the Raman intensity of the symmetric O-H stretching mode, which can account for ∼40% of the total intensity. Meanwhile, a minor destructive interference is found for the angle bending mode. The state-to-state mapping between Albrecht's theory and perturbation theory allows us to verify the accuracy of the widely employed perturbation method for the dynamic/resonant Raman intensities. The model calculations rationalized from water molecule with the bending mode show that the perturbation method is a good approximation only when the absolute energy difference between the first excited state and the incident light is more than five times greater than the vibrational energy in the ground state.
authors.affiliation: Hefei National Laboratory for Physical Science at the Microscale, Department of Chemical Physics, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, 230026 Anhui, People's Republic of China.|Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology , S-106 91 Stockholm, Sweden.
authors.forename: Zu-Yong
authors.initials: ZY
authors.lastname: Gong
authors.affiliation: Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology , S-106 91 Stockholm, Sweden.
authors.forename: Guangjun
authors.initials: G
authors.lastname: Tian
authors.affiliation: Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology , S-106 91 Stockholm, Sweden.
authors.forename: Sai
authors.initials: S
authors.lastname: Duan
authors.affiliation: Hefei National Laboratory for Physical Science at the Microscale, Department of Chemical Physics, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, 230026 Anhui, People's Republic of China.|Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology , S-106 91 Stockholm, Sweden.
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo