Date of Award
Master of Science in Chemical Sciences (MSCB)
We apply and assess the utility of DMD for the purpose of investigating complex spectral features in N2H+···OC, N2D+···OC, C2O4H-, C2O4D- and (HCOOH)2. The proton transfer as a vibrational motion consists of diffuse qualities that can be accounted for with classical and quantum chemical analyses. Classical approaches yield a wealth of information about vibrational spectra at a reduced cost, as in the case of previously investigated N4H+. The isoelectronic N2H+···OC has a smaller dipole moment than N4H+ and a calculated DMD parallel H+ transfer frequency of 1800 cm-1, disagreeing with the VCI (1541 cm-1) and VPT2 (1620 cm-1) values. However, the perpendicular H+ bending mode is evaluated at 910 cm-1, in good agreement with VCI (954 cm-1). Combination bands were recovered at 980 and 1980 cm-1, with weaker absorptions featured at 450 and 380 cm-1. In C2O4H-, the O-H stretch DMD value was in good agreement with the experiment. The brightest experimental peak in the O-H stretching region was ωmax= 2945 cm-1, while the DMD value for the motion was ν1 = 3000 cm-1. C2O4H- combination bands were characterized at 800-850, 1505, and 1450 cm-1 were assigned using the analysis of the atomic motion along the trajectory. Rudimentary explicit solvation effects were explored for C2O4H- and Coupled Cluster PES scans were performed to support all results. A combination band of O-H and C-H in-plane bending was found in the H+ transfer region for (HCOOH)2 using the 2D-IR DMD procedure.
Boutwell, Dalton, "Characterizing the Vibrational Spectra of Hydrogen Bonded Systems with Molecular Dynamics Simulations and Quantum Chemical Methods" (2021). Master of Science in Chemical Sciences Theses. 40.
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