CCQ Seminar: Bryan Lau

Tuesday Aug 11, 2020, 12:00 PM → 1:00 PM America/New_York

Title: Ab-initio molecular adsorption from regional overlap-based embedding

Abstract: The application of wavefunction techniques to problems in periodic systems has been enabled by computational, algorithmic, and theoretical advances in the past decade. Wavefunction techniques offer a systematically improvable hierarchy of methods compared to density functional theory, but suffer from high polynomial scaling with system size. In particular, defects and surface adsorbates in periodic systems break translational symmetry, and large supercells are required to approach the thermodynamic limit. This talk will describe a method to define an active space based upon orbital overlap with the region local to the defect. The calculation of weak van der Waals interaction energies in periodic systems is a stringent test, and overlap-based embedding converges the adsorption energies of water on LiH, hBN, and graphene with a small number of atoms compared to benchmark calculations, due to the dual benefit of performing high-level post-Hartree-Fock calculations on a region around the defect while retaining a large supercell to reduce finite-size and finite-coverage effects. We anticipate that this embedding method can be applied to problems such as the optical properties and formation energies of defects, and heterogenous catalysis.