Title: Computational Molecular Spectroscopy for Astrochemistry and Beyond

Speaker: Dr Laura McKemmish

Abstract: All computational chemists are not the same; obvious but what makes the McKemmish Group at UNSW unique? In brief, spectroscopy, astrochemistry, quantum chemists and data science (for chemists).

In more detail, one of our key motivations is to predict spectral data that is useful, often for characterising unusual astrophysical environments. Sometimes this means very high accuracy sub-cm-1 predictions of rovibronic spectra of weird diatomics like TiO, using all the experimental data we can find. Other times, this means producing approximate data for thousands of molecules to identify strong absorbers and molecules that will be difficult to distinguish astrophysically as well as trying to recreate organic chemistry infrared functional group tables.

We are quantum chemists interested in high-accuracy methods for small molecules and huge fans of thorough benchmarking. Like all quantum chemists, we will get upset when you use B3LYP without a good justification, but we specialise in also getting upset when you use 6-311+G and reminding you that NMR properties depend on core electrons so you need a specialised or very large basis set. Besides benchmarking basis set performance, we are also quantifying expected errors for vibrational frequency calculations to figure out whether B3LYP/6-31G* really is good enough for this application.