Electronic Structure and Isomerization of Stilbene

Abstract

The electronic structures of trans‐ and cis‐stilbene are calculated using Pariser and Parr's semiempirical method. The resonance integrals are adjusted so as to give the best agreement with the spectroscopic data. In addition, the potential surfaces of various excited states in stilbene during its isomerization process are calculated. Our results differ significently from those of Borrell and Greenwood2) who did not realized the importance of a doubly excited singlet state to the potential surface of the ground state of stilbene. Our improved potential surfaces suggests mechanism of various radiationless leading to photoisomerization and sensitized isomerization.

Dark matter daily modulation with anisotropic organic crystals

“…where α is the fine-structure constant, r ij = |r i − r j |, and the sum runs over all pairs of electrons ij with i = j. This PPP Hamiltonian perturbs the energy levels of the ψ j i configurations and mixes degenerate states of like symmetries to produce PPP HMOs of either A g or B u symmetry [59,61,62] are expressed as a linear combination of ψ j i ,…”

“…8 excited states of t-stilbene are tabulated in Tab. I [59]. To better match our analysis to experimental data, we take the experimentally-determined energy eigenvalues, which are also listed in Tab.…”

“…To better match our analysis to experimental data, we take the experimentally-determined energy eigenvalues, which are also listed in Tab. I [59].…”

Stilbene. A critical commentary and some new calculations on its structure and isomerization

“…Potential energy surfaces for the c-t isomerism of stilbene have been calculated in a number of semiempirical MO models. 26,28,29,31,32,34,41 Most of these26, 31,32,34,41 are restricted to the x electrons and therefore neglect the effect of hyperconjugation, which is expected to be greatest in the region of the perpendicular configuration. In all cases, a C2 axis of symmetry has been maintained during the course of the reaction.…”

“…This does not seem likely, but a triplet potential surface with the geometrical features in question has in fact been calculated for stilbene by Ting and McClure (TM). 31 The cis-trans isomerism of stilbene is a "thermally forbidden, photochemically allowed" reaction in the Woodward-Hoffmann sense. 46 Accordingly, the adequacy of different molecular orbital (MO) models for constructing potential energy surfaces for such reactions and for constructing wave functions for diradicals is reviewed briefly in section II.…”