In this work, we predict the vibrational spectra of N2H+…OC linear complex using Molecular Dynamics (MD), Driven Molecular Dynamics (DMD), Vibrational Self-Consistent Field Theory (VSCF), and Vibrational Configuration Interaction theory (VCI) methods. N2H+…OC represents a medium-sized molecular system that can exist in the interstellar medium (ISM). Computational chemistry approaches can predict vibrational spectra, hence facilitate prediction of its existence and stability in the ISM. N2H+…OC involves the proton transfer process via hydrogen bonding interaction. Proton motion is highly anharmonic, therefore facing a significant challenge to characterize it accurately. Quantum mechanical variational methods are popular among many theoretical chemists for their efficiency producing accurate results. DMD simulations present an alternative route to predicting and assignment of infrared spectra. The N2H+…OC complex, is an important intermediate in the isomerization of COH+ to HCO+, with no published experimental results. We test the accuracy and performance of the MP2/aug-cc-pVDZ and CCSD(T) levels of theory by comparing theoretical and available experimental spectra for a similar complex N4H+. We report a metastable distorted T-shaped structure along the isomerization pathway of N2H+…OC to N2…HCO+. Molecular vibration involving proton transfer along the molecular axis appears at ~1780 cm-1 predicted by both VSCF and DMD methods. This work provides an overview of IR spectra, line positions, and mode assignment that allows experimentalists to detect molecules quickly.

Computer simulations of vibrational spectra of N2H+…OC complex assisting spectroscopic observation in interstellar medium

ACS Fall 2020 Virtual Meeting

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