Kinetics of bimolecular chemical reaction by a modified diffusion equation

In order to describe the kinematical behavior of the bimolecular chmical reaction in a dilute solution of species characterized by a single diffusion coefficient and by some nonuniform spatial distribution of the active site, a diffusion equation with a simple sink term is derived by reducing the many-body problem to a one-body problem. The equation is normalized with the concentration of unreacted particles. The so-called second-order reaction rate constant can be calculated from the solution of the equation. The equation is applied to the intermolecular termination reaction of polymer radicals on the assumption of free draining. The reaction rate constant gradually decreases with time.     

Geometry optimization using symmetry coordinates

The use of symmetry coordinates (SC ) in geometry optimization is discussed. A computer program incorporating the use of sc, together with analytical calculation of the gradient and quadratic acceleration, is described. Also reported are careful test results on a series of small molecules and typical results with a long series of molecules up to quite large size (40–60 atoms).     

Resolution enhanced Ni Kα and Kβ spectra obtained by the deconvolution method

Ni K_α, and K_β spectra of NiO, NiF₂, and NiS were measured using a vacuum two-crystal high resolution X-ray spectrometer. In order to make clear fine structures due to multiplet splitting, numerical deconvolution with the lifetime broadening factor as a deconvoluting function was carried out in the frequency domain using a successive pseudo-deconvolution technique. Based on extensive simulation studies, the most appropriate polynomial smoothing function was chosen from among those given by Savitzky and Golay [Anal. Chem.36. 1627 (1964)]. The quartic 17-point and 11-point smoothing convolute functions were used for processing observed K_β and K_α spectra. Results obtained by a simple jj-coupling model including exchange interactions between two incomplete shells do not seem to be consistent with the deconvolution results.