Search

An efficient vector processing algorithm generating PK supermatrices has been developed, in particular aiming at calculations on large molecules. The algorithm utilizes the recurrence relations for electron repulsion integrals. The PK supermatrices are listed in a nearly canonical order so that the Fock matrix generation is efficiently vectorized, no temporary ERI and PK files being used. This is effected by partition of the basis set (atomic orbitals) into subsets of certain appropriate sizes, and the partition approach is named as the three-dimensional partial space method. A high-speed Hartree–Fock calculation including integrals and SCF procedures is achieved. © 1992 by John Wiley & Sons, Inc.

A six-term auxiliary integral expression for the two-electron Gaussian integral is derived on the basis of the Chebyshev polynomial approximation instead of the seven-term Taylor expansion. This expression and the related recurrence formula enable us to perform a high-speed calculation on a vector processing computer.

The radical species derived from cyclopentane, cyclopentenes and cyclohexenes by 60Co γ-ray irradiation at 77 K in halocarbon matrices have been studied by ESR spectroscopy. The electronic and geometrical structures of the radical species are discussed on the basis of the experimental hyperfine coupling constants and semiempirical MO calculations. Exposure of the tetramethylsilane frozen solution containing cyclopentene to 60Co γ-rays produced specifically 3-cyclopenten-l-yl.

Lasing wavelengths and fluorescence spectra were measured for a mixed dye system containing various concentrations of Rhodamine 6G (Rh-6G) and 3,3′-dietriylthiacarbocyanine iodide (DTC), which have very closely located S1 levels, in acetone at room temperature. A new way of confirming the occurrence of energy transfer is presented on the basis of the reabsorption effect. It was found that most of the pump power absorbed by Rh-6G is transferred to DTC. A study of the fluorescence decay by a picosecond laser revealed that the energy transfer is essentially governed by the Forster mechanism. The observed fluorescence decay data agree fairly well with the R0 value of 73.2 A calculated from the spectral overlap.

The laser and fluorescence behavior was studied for the mixed dye system containing various concentrations of 3,3′-diethylthiacarbocyanine iodide and rhodamine 6G. A new way of confirming the occurrence of energy transfer is presented on the basis of the reabsorption effect.