Takayoshi Ishimoto

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Deuterium isotope effects measure the change in chemical shift on substitution of a proton by deuterium. They have been calculated by direct treatment of the H/D nuclear quantum effect using a multicomponent ab initio molecular orbital method based on a non-Born-Oppenheimer approximation. This method enables the determination of both the electronic and the(More)
We analyzed the interaction energies between residues (fragments) in an oligopeptide occurring during dynamic simulations by using the fragment molecular orbital-Hamiltonian algorithm (FMO-HA) method, an ab initio MO-molecular dynamics technique. The FMO method enables not only calculation of large molecules based on ab initio MO but also easy evaluation of(More)
We theoretically analyzed the chemical degradation mechanism of Nafion side chain by OH radicals on the basis of density functional theory calculations. We found that the cleavage of the C–O bond in ether groups is a main pathway of the degradation from the Nafion side chain by OH radicals under well-hydrated condition. The ether group, which is located(More)
The geometric isotope effect (GIE) of sp- (acetylene-water), sp(2)- (ethylene-water), and sp(3)- (methane-water) hybridized intermolecular C-H...O and C-D...O hydrogen bonds has been analyzed at the HF/6-31++G level by using the multicomponent molecular orbital method, which directly takes account of the quantum effect of proton/deuteron. In the(More)
The geometric and kinetic isotope effects (GIE and KIE) for thermal [1,5]-sigmatropic H and D shifts of (Z)-1,3-pentadiene were studied by including the direct quantum effect of the migrating H or D nucleus in the multi-component molecular orbital-Hartree-Fock (MC_MO-HF) method. Based on the results, the C(1)-D bond lengths are 0.007 Angstrom shorter than(More)
Rotationally resolved ultrahigh-resolution spectra of the S(1) (1)B(2u)<--S(0) (1)A(g) transition of anthracene-h(10) and anthracene-d(10) have been observed using a single-mode UV laser and a collimated supersonic jet. We have determined rotational constants of the zero-vibrational levels of the S(0) and S(1) states by analyzing the precisely calibrated(More)
A parallel Fock matrix construction program for FMO-MO method has been developed with the distributed shared memory model. To construct a large-sized Fock matrix during FMO-MO calculations, a distributed parallel algorithm was designed to make full use of local memory to reduce communication, and was implemented on the Global Array toolkit. A benchmark(More)
To understand the origin of the physicochemical nature of bimetallic PdPt nanoparticles, we theoretically investigated the phase stability and electronic structure employing the PdPt nanoparticles models consisting of 711 atoms (ca. 3 nm). For the Pd-Pt core-shell nanoparticle, the PdPt solid-solution phase was found to be a thermodynamically stable phase(More)
Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements(More)
Fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled 9-methylanthracene-h12 and -d12 (9MA-h12 and 9MA-d12) have been observed, and the energy levels of methyl internal rotation (CH3 torsion) in the S0 and S1 states have been analyzed. The molecular symmetry of 9MA is the same as that of toluene (G12). Because of two-fold symmetry(More)