Photoinduced phase transition models between two distinct structures (acetylene and butatriene types) of polydiacetylene were investigated by using an elongation method. The geometries of these oligomers were optimized with ab initio self-consistent field. The wave functions for the calculation of the excitation energies were obtained with complete neglect of differential overlap in spectroscopy (CNDO/S approximation) by the elongation method. The excitation energies were calculated by using the single excitation configuration interaction method on the basis of localized molecular orbitals. The energy diagram for the phase transition is plotted and the structural change associated with the photoinduced excitation is discussed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry