2023/09/26 by Annabelle Canestraight, Xiaohe Lei, Canestraight, Annabelle +5
Engineering · Physics and Astronomy · #Advanced Chemical Physics Studies #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Molecular Junctions and Nanostructures #Surface and Thin Film Phenomena
paper · pdf · doi:10.48550/arxiv.2309.15258
openalex publication_date 2023/09/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Calculations of excited states in Green's function formalism often invoke the diagonal approximation, in which the quasiparticle states are taken from a mean-field calculation. Here, we extend the stochastic approaches applied in the many-body perturbation theory and overcome this limitation for large systems in which we are interested in a small subset of states. We separate the problem into a core subspace, whose coupling to the remainder of the system environment is stochastically sampled. This method is exemplified on computing hole injection energies into CO2 on an extended gold surface with nearly 3000 electrons. We find that in the extended system, the size of the problem can be compressed up to 95% using stochastic sampling. This result provides a way forward for self-consistent stochastic methods and determining Dyson orbitals in large systems.