An Accurate, Affordable Density Functional Tight-Binding Model for Excited State Hydrocarbon Polymer Molecular...

We have developed a density functional tight-binding model for hydrocarbon excited state dynamics by referencing to high-level electronic structure theory and incorporating a many-body repulsive energy. We then validate our model against n-octane geometry optimizations, bond dissociation scans, and vibrational frequencies. Our model is approximately 10³ times more efficient than hybrid time-dependent density functional theory calculations with comparable accuracy. Our efforts enable longer timescale excited state simulations of photochemistry and scattering of incident radiation.