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Updated: May 11, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Stochastic determination of effective Hamiltonian for the full configuration interaction solution of quasi-degenerate
1Graduate School of System Informatics, Department of Computational Sciences, Kobe University, Nada-ku, Kobe, Japan. tenno@cs.kobe-u.ac.jp
Abstract:
We propose a novel quantum Monte Carlo method in configuration space, which stochastically samples the contribution from a large secondary space to the effective Hamiltonian in the energy dependent partitioning of Löwdin. The method treats quasi-degenerate electronic states on a target energy with bond dissociations and electronic excitations avoiding significant amount of the negative sign problem. The performance is tested with small model systems of H4 and N2 at various configurations with quasi-degeneracy.
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