Evolution of physical properties of conjugated systems

Authors

  • Wun-Fan Li,

    1. Institute of Molecular Science, National Chiao Tung University, 1001 Ta Hsueh Road, 30010 Hsinchu, Taiwan
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  • Marcin Andrzejak,

    1. Institute of Molecular Science, National Chiao Tung University, 1001 Ta Hsueh Road, 30010 Hsinchu, Taiwan
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    • On leave from Faculty of Chemistry, Jagiellonian University, Krakow, Poland

  • Henryk A. Witek

    Corresponding author
    1. Institute of Molecular Science, National Chiao Tung University, 1001 Ta Hsueh Road, 30010 Hsinchu, Taiwan
    2. Department of Applied Chemistry, National Chiao Tung University, 1001 Ta Hsueh Road, 30010 Hsinchu, Taiwan
    • Phone: +886 35712121, ext: 56583, Fax: +886 35723764
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  • Dedicated to Thomas Frauenheim on the occasion of his 60th birthday

Abstract

Evolution of various physical properties of finite conjugated systems with increasing molecular size is studied using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. We usually observe a transition from the finite to the infinite regime for surprisingly short molecular chains containing only 20–30 monomer units of cis-butadiene, cyclopentadiene, pyrrole, furan, and thiophene. Such a fast convergence of equilibrium geometries, induced atomic charges, electron densities of states (DOS) and energy gaps, dipole and quadrupole moments, and polarizabilities is particularly striking considering the presence of strong π-conjugation.

original image

Convergence in the size evolution of majority of molecular properties of conjugated systems occurs for surprisingly short molecular chains.

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