A Pariser-Parr-Pople (PPP) Hamiltonian of an 8pi; electron system of the molecule octatetraene, represented in a configuration-interaction basis (CI basis), is analyzed with respect to the statistical properties of its matrix elements. Based on this analysis we develop an effective Hamiltonian, which represents virtual excitations by a Gaussian orthogonal ensemble (GOE). We also examine numerical approaches which replace the original Hamiltonian by a semistochastically generated CI matrix. In that CI matrix, the matrix elements of high energy excitations are choosen randomly according to distributions reflecting the statistics of the original CI matrix.
|Original language||English (US)|
|Number of pages||11|
|Journal||The Journal of Chemical Physics|
|State||Published - 1992|
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry