Abstract (300 words maximum)
A substantial advancement in the understanding of the Raman scattering behavior in complexes has occurred in the past decades, with various modifications for the Raman experimental technique, such as the development of Surface Enhanced Raman spectroscopy (SERS), spatially offset Raman spectroscopy, transmission Raman spectroscopy that permits the investigation of the vibrational Raman spectra directly complimentary to the infrared spectra. We developed and implemented polarizability tensor surfaces (PTS) fitted to the analytical form that utilizes more accurate methods MP2(many-body perturbation theory to the second order) and CCSD(T) (coupled-cluster) to run molecular dynamics (MD) simulations and identify and visualize vibrational motion. Three model systems H5O2+, N4H+, and CH4 are investigated using our techniques. Simulated vibrational spectra are compared to available experimental results to validate our theoretical methods. We also analyze anharmonic effects such as Fermi resonance doublet for the H5O2+ in the mid-range IR region, combination bands, and overtones for the N4H+ using driven molecular dynamics (DMD) method and evaluated computational efficiency of various PTS models for CH4. This work contributes to the better understanding of anharmonic spectral features in hydrogen bonded systems and facilitates detection of gas-phase molecules.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Martina Kaledin
Elucidating Raman Spectra of Molecules Through Ab Initio Classical Molecular Dynamics Simulations
A substantial advancement in the understanding of the Raman scattering behavior in complexes has occurred in the past decades, with various modifications for the Raman experimental technique, such as the development of Surface Enhanced Raman spectroscopy (SERS), spatially offset Raman spectroscopy, transmission Raman spectroscopy that permits the investigation of the vibrational Raman spectra directly complimentary to the infrared spectra. We developed and implemented polarizability tensor surfaces (PTS) fitted to the analytical form that utilizes more accurate methods MP2(many-body perturbation theory to the second order) and CCSD(T) (coupled-cluster) to run molecular dynamics (MD) simulations and identify and visualize vibrational motion. Three model systems H5O2+, N4H+, and CH4 are investigated using our techniques. Simulated vibrational spectra are compared to available experimental results to validate our theoretical methods. We also analyze anharmonic effects such as Fermi resonance doublet for the H5O2+ in the mid-range IR region, combination bands, and overtones for the N4H+ using driven molecular dynamics (DMD) method and evaluated computational efficiency of various PTS models for CH4. This work contributes to the better understanding of anharmonic spectral features in hydrogen bonded systems and facilitates detection of gas-phase molecules.