Raman vibrational spectra of H5O2+ protonated water dimer and its deuterated analogs D5O2+, D4HO2+, and H4D+O2. were calculated using the normal mode analysis (NMA) at the MP2/ aug-cc-pVTZ (AVTZ) level of theory and molecular dynamics simulations. The analytical potential energy (PES), dipole moment surface (DMS), and molecular polarizability tensor surfaces at the CCSD(T)/AVTZ, MP2/AVTZ, and CCSD(T)/AVTZ(O:spd, H:sp), respectively were used. Proton motion in H5O2+ yields high IR activities near 1000 cm-1, while OH-stretch vibrations show strong Raman activities. The Raman spectra of H5O2+ frequencies showed high-intensity peaks for OH stretch vibrations at 3736 cm-1, 3810 cm-1, and a weak spectral feature near 500 cm-1 tentatively assigned to O…O stretch vibration. The deuterated analog D5O2+showed OD stretch vibrational modes at 2692 cm-1 and 2795 cm-1. Currently, we are running the molecular dynamics simulations for other deuterated analogs D4HO2+, and H4D+O2 to obtain IR and Raman spectra. This computational work will provide the baseline information to assess the anharmonic effects in the vibrational spectra.

Molecular dynamics simulations of the Raman vibrational spectra of H5O2+ and its deuterated analogs

ACS Spring 2022

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