Post Semiempirical Quantum Chemistry Methods

J. Keith, B. Zulueta, M. Plum, C. Mhatre, M. Marciesky, V. Kam

Accurate quantum chemical predictions remain computationally expensive for navigating large chemical spaces. This talk will report our recent advances in developing post-semiempirical quantum mechanics (Post-SEQM) methods that leverage well-conditioned minimum basis set orbital populations and exploit tight-binding relationships across chemical space. We will start by focusing on the Bond Energy from Bond Orders and Populations (BEBOP) approach, which is rooted in tight-binding theory. BEBOP delivers surprisingly accurate approximate atomization energies that are decomposed into intuitive intramolecular bond energy contributions from a single self-consistent quantum chemistry calculation. We will highlight an application of BEBOP in chemical design of processes for plastic recycling. We will also introduce extension to BEBOP theory that are useful for predicting thermochemically relevant vibrational energy contributions without the computational burden of Hessian calculations. Finally, I will show progress in developing the Pittsburgh Approximate Molecular Orbital (PAMO) method that strives to reproduce chemical bonding from Hartree-Fock theory with a large basis set. These topics will be presented to demonstrate how Post-SEQM methods can accelerate computational screening and rational design across chemical compound space.