Relaxed Excited State Geometries in a Peierls-Hubbard Model for Polyenes

TL;DR

This paper uses exact finite size diagonalization of a Peierls-Hubbard model to analyze relaxed geometries and optical spectra of polyenes, providing insights into how well the model captures their electronic properties.

Contribution

It demonstrates the effectiveness of a simple Peierls-Hubbard model in reproducing the geometries and optical spectra of polyenes through exact diagonalization.

Findings

Accurate geometries for various electronic states of polyenes.

Reproduction of optical absorption spectra consistent with experiments.

Validation of the Peierls-Hubbard model for simple conjugated polymers.

Abstract

Using parameter values relevant to polyacetylene and its finite polyene analogs, we determine, via exact finite size diagonalization of a 1D Peierls-Hubbard model, the relaxed geometry and optical absorption spectra of several states of interest in optical experiments (the singlet ($1^1A_g$) and triplet ($1^3B_u$) ground states, the singlet one ($n^1B_u$) and two ($2^1A_g$) photon gaps, and the triplet one ($n^3A_g$) photon gap) in order to examine the question of how well this simple model can really capture the behavior of this simple material.