Multisite bond and overlap treatment of polymer-chain band structure.

The usual tight-binding (TB) approximation, employed in electronic structure calculations, is extended to include the more-distant neighbor sites than the first. In doing so, a simple power law is adopted to describe the bond and overlap contributions, which enables the energy dispersion relation to be obtained in a closed analytic form. The resulting energy band structure has markedly different features from its TB counterpart to which it reduces in the appropriate limits. In particular, local extrema always occur at the TB stationary values, although these may not both be band edges. Another intermediate critical point may arise, which is one of the band edges, the other being located at one of the TB extrema. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 341–346, 2003 [ABSTRACT FROM AUTHOR]