Green's function formalism provides a convenient framework for describing electronic excitation in extended and condensed phase systems. Further, it is commonly used in many-body perturbation theory to capture dynamical correlations in weakly and moderately correlated systems via the non-local and dynamical self-energy. I will introduce our recently developed approaches based on the vertex-corrected self-energies accounting for nontrivial mutual quasiparticle interactions. The theory is combined with efficient stochastic numerical methods that sample single-particle states, propagators, and interactions. As such, the framework can tackle huge systems with hundreds and thousands of atoms, and it is an ideal platform for simulating complex nanoscale systems. I will also present our recent work that efficiently combines stochastic methods with embedding and ab-initio downfolding on explicitly correlated Hamiltonian. A self-consistent perturbation theory step identifies the correlated subspace, and the embedding/downfolding procedure provides renormalized two-particle interactions within the subspace. The computational cost is minimal, and I will exemplify the methodology on quasiparticle calculations for defect states in low dimensional semiconductors and localized moire electronic states in twisted bilayer graphene.

Decomposition, downfolding, and embedding in vertex-corrected and self-consistent stochastic many-body perturbation theory

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.