Semiempirical treatment of the benzophenone molecule as a function of twist angle

摘要

The benzophenone molecule has been treated in MNDO, MNDOC, and MINDO/3 approximation as a function of the twist angle agr; of the phenyl rings. Calculated were (i) the energies ofS0andT1state, (ii) delocalization of thenand pgr;ast; orbitals involved in the3npgr;ast; state, (iii) net atomic charges,(iv) the force constants of the C=O vibration in theS0andT1state, respectively, (v) vertical transition energies forT1larr;S0andS1larr;S0, and (vi) the position of upper triplet states. The results are discussed in relation to the spectroscopic properties of theT1state of a vitreous benzophenone phase. It is concluded that diagonal disorder is due to a significant fluctuation of agr; causing both a spread of the site energies of the glasshyphen;forming molecules and a variation of spinhyphen;orbit coupling.