MOLECULAR-ORBITAL COEFFICIENTS AND TRANSITION DIPOLES OF REAL POLYENES

A simple four configuration model that quantitatively reproduces all o f the 1(1)B(u) and 2(1)A(g) state 0-0 energies that have been measured in high resolution spectroscopic experiments has been described previ ously. This model has been useful for explaining trends in the electro nic properties of series of unsubstituted and substituted linear polye nes. While this model led to analytical expressions for the excitation energies, there were no closed form expressions for other quantities, such as the transition dipoles, that depend explicitly on the coeffic ients of the one-electron molecular orbitals. This paper derives exact expressions for the one-electron molecular orbital coefficients for a n alternating chain as well as exact expressions for the transition di pole moments. This facilitates a detailed examination of the dependenc e of the transition dipole moments on the polyene length and alternati on parameter which leads to an expression that accurately describes th e dependence of the transition dipole moments on these chain parameter s. The application of these expressions to an analytical analysis of n onlinear response in Linear polyenes will be the subject of a subseque nt paper. (C) 1995 American Institute of Physics.