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

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 ($1^1{A}_g$) and triplet ($1^3{B}_u$) ground states, the singlet one ($n^1{B}_u$) and two ($2^1{A}_g$) photon gaps, and the triplet one ($n^3{A}_g$) photon gap) in order to examine the question of how well this simple model can really capture the behavior of this simple material.

3 Figs (appended)