Combining Effective Hamiltonians and Brillouin-Wigner Approach: A Perturbative Approach to Spectroscopy

2024/08/29 by Oussama Bindech, Bindech, Oussama, Bastien Valentin +5 · 1 citation
Physics and Astronomy · #Atomic and Subatomic Physics Research #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Quantum optics and atomic interactions #Spectroscopy and Quantum Chemical Studies

paper · pdf · doi:10.48550/arxiv.2408.16505

openalex publication_date 2024/08/29 · openalex created_date 2024/09/22 · openalex updated_date 2026/07/28

Abstract

The numerical cost of variational methods suggests using perturbative approaches to determine the electronic structure of molecular systems. In this work, a sequential construction of effective Hamiltonians drives the definition of approximate model functions and energies in a multi-state Rayleigh-Schrödinger perturbative scheme. A second step takes advantage of an updated partitioning of the Hamiltonian to perform a state-specific Brillouin-Wigner energy correction based on a well-tempered perturbation expansion. The multi-step RSBW method is exemplified on model-Hamiltonians to stress its robustness, efficiency and applicability to spectroscopy determination.

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