Abstract

Molecules in the ‘X-C≡N’ chemical family serve as markers for chemical processes happening in various regions of space and are members of the prebiotic molecular pool, which makes them important in astrochemistry and astrobiology. Although these kinds of molecules have been identified in the interstellar medium, cometary comae, plumes of Enceladus, meteorites, and around young stellar objects, it is not clear which mechanisms are responsible for their formation. However, it has been suggested that they may serve as precursors to prebiotically important compounds, such as amino acids and nucleobases. In this work, a theoretical computational study was conducted using quantum mechanical approaches to predict properties of sixteen astrochemically relevant ‘X-C≡N’ molecules. To perform this study, General Atomic and Molecular Electronic Structure System (GAMESS(US)) and AutoGAMESS software were used to calculate optimized geometries, harmonic vibrational frequencies, infrared intensities, and Raman activities of each molecule using density functional theory (BLYP, B3LYP, PBE, and PBE0) and second order Møller-Plesset perturbation theory (MP2, SCS-MP2) paired with several basis sets (6-311++G(d,p), def2QZVPD, Sadlej-pVTZ, and aug-cc-pVQZ). Geometries and frequencies were additionally calculated using coupled cluster approaches (CCSD, CCSD(T), and CCSD(2)T) to help assess accuracy and reliability of the other calculations. For many of these species, experimentally and computationally determined Raman activities have not been reported in the literature. We assess the reliability of our calculations in comparison to previous works and discuss how the implementation of both Raman and infrared spectroscopy can offer new insights into potential reaction mechanisms linking these prebiotically relevant compounds.

Thesis Completion

2022

Semester

Spring

Thesis Chair/Advisor

Bennett, Christopher

Degree

Bachelor of Science (B.S.)

College

College of Sciences

Department

Physics

Degree Program

Physics

Language

English

Access Status

Campus Access

Length of Campus-only Access

1 year

Release Date

11-1-2023

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