High-level quantum calculations using quartic force fields have recently shown the ability to reproduce experimental vibrational frequencies to within 1.0 cm<sup>-1</sup> for small hydrocarbon molecules. The level of theory required to achieve this accuracy makes these calculations intractably expensive for systems beyond a few atoms and are thus not applicable to study astrochemically relevant molecules like polycyclic aromatic hydrocarbons (PAHs). Our group has reparametrized semi-empirical electronic structure methods using the high-level vibrational potential energy surfaces to calculate spectroscopic constants for astrochemically relevant molecules and ions. These reparametrized semi-empirical methods are orders of magnitude faster than this high-level methods and fit the vibrational potential with RMSEs of less than 0.8 cm<sup>-1</sup>. Our newly parametrized semiemprirical methods are able to accurately predict molecular geometries, rotational constants, and anharmonic vibrational corrections for homologous molecules. These transferability of these methods study small PAH systems are currently being tested and initial calculations towards this goal will be presented

Semi-empirical anharmonic vibrational calculations of astrochemical species

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.