The Duschinsky effect has been shown to be significant in spectroscopy and dynamics of molecules that involve the π−π* transitions. In this paper, we present a derivation of exact expressions for optical absorption and radiationless transitions in polyatomic molecules with displaced−distorted−rotated harmonic potential surfaces. In the formulation, we take into account the temperature effect exactly. The application of this new formulation is demonstrated for ethylene and allene, where the Duschinsky effect in the first singlet excited electronic state is very strong.

A statistical-mechanical treatment of the solubilization in micelle is presented in combination with molecular simulation. The micellar solution is viewed as an inhomogeneous and partially finite, mixed solvent system, and the method of energy representation is employed to evaluate the free-energy change for insertion of a solute into the micelle inside with a realistic set of potential functions. Methane, benzene, and ethylbenzene are adopted as model hydrophobic solutes to analyze the solubilization in sodium dodecyl sulfate micelle. It is shown that these solutes are more favorably located within the micelle than in bulk water and that the affinity to the micelle inside is stronger for benzene and ethylbenzene than for methane. The micellar system is then divided into the hydrophobic core, the head-group region in contact with water, and the aqueous region outside the micelle to assess the relative importance of each region in the solubilization. In support of the pseudophase model, the aqueous region is found to be unimportant to determine the extent of solubilization. The contribution from the hydrophobic-core region is shown to be dominant for benzene and ethylbenzene, while an appreciable contribution from the head-group region is observed for methane. The methodology presented is not restricted to the binding of a molecule to micelle, and will be useful in treating the binding to such nanoscale structures as protein and membrane.

The binding interactions between the pyridine and small noble metal clusters in different sizes (n ) 2-4) have been investigated by using quantum chemical methods. The binding energies of Py-M 2 complexes are obtained at the levels of the Hartree-Fock method (HF), the second-order Møller-Plesset perturbation theory (MP2), the local density functional method (SVWN), the nonlocal density functional method (BLYP, BPW91, G96LYP, G96PW91), and the hybrid density functional method (B3LYP and B3PW91). All calculated results show that the bonding is stronger in pyridine/copper and pyridine/gold than that in pyridine/silver. The bonding mechanism is explored in terms of the bonding molecular orbital properties. The donation interaction of the lone-pair electrons on nitrogen of the pyridine molecule to the unoccupied orbital of each metal cluster plays an important role. The force constants of the internal coordinates of interests are presented. The vibrational frequency shift has been analyzed on the basis of the coupling between the internal vibrational modes of pyridine and the nitrogen-metal stretching modes as well as the metal-metal stretching modes. For lowfrequency Raman spectra of pyridine-small silver cluster complexes, we propose a new assignment to the N-Ag and Ag-Ag stretching vibrations. The calculated infrared intensities of vibrational modes are compared with the experimental spectra.