1997/03/13 by Zhigang Shuai, Z. Shuai, J. L. Bredas +4 · 1 citation
Materials Science · Physics and Astronomy · #Organic and Molecular Conductors Research #Quantum and electron transport phenomena #Spectroscopy and Quantum Chemical Studies #cond-mat
paper · pdf · doi:10.1103/physrevb.56.9298
Latex file; figures available upon request. Submitted to PRL
arxiv created 1997/03/13 · openalex publication_date 1997/10/15 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The symmetrized density-matrix renormalization-group approach is applied within the extended Hubbard-Peierls model (with parameters U/t, V/t, and bond alternation \ensuremathδ) to study the ordering of the lowest one-photon (11Bu^\ensuremath-) and two-photon (21Ag+) states in one-dimensional conjugated systems with chain lengths N up to N=80 sites. Three different types of crossovers are studied, as a function of U/t, \ensuremathδ, and N. The ``U crossover'' emphasizes the larger ionic character of the 2Ag state compared to the lowest triplet excitation. The ``\ensuremathδ crossover'' shows strong dependence on both N and U/t. the ``N crossover'' illustrates the more localized nature of the 2Ag excitation relative to the 1Bu excitation at intermediate correlation strengths.