Coupled cluster-based quartic force fields have been the workhorse of rovibrational spectroscopic predictions for the past decade at least.  They have been able to predict vibrational frequencies to within 1 cm<sup>-1</sup> of experiment in some cases and rotational constants to within a few dozen MHz, as well, and have even predated laboratory and astronomical detections.  We have applied such approaches to anions, noble gas compounds, proton-bound complexes, and even electronically excited states for rovibronic analysis with much success.  Now, magnesium-bearing compounds and polycyclic aromatic hydrocarbons (PAHs) are the focus.  Stars known to host rocky planets are also known to possess higher [Mg]/[Fe] ratios than stars known not to host planets.  Hence, premineral, Mg-bearing molecules could act as screeners for exoplanet searches, but the data for such molecules are nearly-nonexistent.  We have begun to provide such data for magnesium oxides and are growing our chemical inventory.  Additionally, neutral PAHs are exceptionally difficult to isolate in the laboratory making classification of their individual spectra nearly impossible.  Computationally, they are huge and require vast resources to compute any data.  However, we are training semi-empirical methods to treat these systems accurately.  Initial results for this aspect of the research will also be presented.

Answering unique spectroscopic and astrochemical problems through quantum chemistry

255th National Meeting (2018)

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