Local Structures of AgxCu1-xI by means of NMR, ab initio MO and MD methods

取得学位: 博士(理学), 授与番号: 甲第1895号, 授与年月日: 平成13年3月22日, 授与大学: 金沢大

A comparative theoretical study of the hydride transfer mechanisms during LiAlH4 and LiBH4 reductions

This work examined the hydride transfer processes during the reduction of formaldehyde by LiAlH4 or LiBH4, including investigations of the geometries, solvent effects and charge transfer processes along the reaction coordinate, using density functional theory (DFT). The energy and geometry results demonstrate that the transition state (TS) structure for the LiAlH4-formaldehyde complex is reactant-like, while the structure generated by LiBH4 has a product-like geometry, consistent with the Hammond postulate. From a charge density analysis, we also found that both complexes undergo the same essential hydride transfer mechanism, which consists of: (1) single electron transfer to the carbonyl carbon, (2) formation of a bridge bond (X-H-C; X=Al or B) and (3) hydrogen transfer driven by electron transfer. Subsequently, in a fourth step, a single electron flows through the X-H-C bond during transfer of the hydrogen, such that hydrogen atom or proton-coupled electron transfer occurs. In both systems, the presence of tetrahydrofuran as a solvent affects the structure and energy values during the reaction, but not the charge transfer characteristics. We propose that the rate-determining steps during hydride transfer when employing LiAlH4 and LiBH4 are one electron transfer to the carbonyl carbon and B-H bond dissociation, respectively. © 2015 Elsevier B.V.Embargo Period 24 month

NMR,分子軌道法および分子動力学法によるAgxCu1-xIの局所構造解析

取得学位：博士(理学)，学位授与番号：博甲第375号，学位授与年月日：平成13年3月22日,学位授与年：200

Simulation of molecular Auger spectra using a two-electron Dyson propagator

In order to simulate Auger electron spectra (AES), we propose the use of the two-electron Dyson propagator with the shifted denominator approximation (SD2). The double ionization potentials (DIPs) of molecules calculated using the SD2 method have shown good agreement with experimental data. This method can be used to calculate each DIP separately, and reducing the matrix dimensionality into that of only a two-hole configurations. We carried out AES simulations of water (H2O), ethylene (C2H4), and formaldehyde (H2CO) molecules and compared with the observed spectra. Furthermore Auger line shapes of glycine and hydrated glycine molecules were simulated, it found out that the peaks of nitrogen K-LL Auger were broadened due to hydration. From these results, we conclude that the SD2 method is very useful for the calculation of DIPs to investigate the properties of a double ionized molecule. © 2016 Elsevier B.V. All rights reserved.Embargo Period 24 month

Fragment distribution of thermal decomposition for PS and PET with QMD calculations by considering the excited and charged model molecules

金沢大学理工研究域物質化学系Simulations by a quantum molecular dynamics (QMD) (MD with MO) method were demonstrated on the thermal decomposition of PS and PET polymers using the model molecules at the ground state including excited and positive charged states. For the excited and positive charged model molecules, we adopted CH3CHC6H5CH3 and CH3OCOC6H4COOCH3 of PS and PET monomers, respectively at the singlet and triplet states in single excitation, and at (+2) positive charged state by semiempirical AM1 MO method. Geometry and energy optimized results of the excited and positive charged models by MO calculations were used as the initial MD step of QMD calculations. In the QMD calculations, we controlled the total energy of the system using Nosé-Hoover thermostats in the total energy range of 0.69-0.95 eV, and the sampling position data with a time step of 0.5 fs were carried out up to 5000 steps at 60 different initial conditions. The calculated neutral, positive and negative charged fragment distributions of PS and PET models with 0.82 eV energy control were obtained as (93.5, 2.3, and 4.3%), and (87.8, 5.3, and 6.9%) to the total fragments, respectively. The ratios seem to correspond well to the values observed experimentally in SIMS. Crown Copyright © 2008

X-ray fluorescence study of organic-inorganic polymer conversion into ceramics induced by ion irradiation

金沢大学理学部Changes to the local and electronic structures of phenyltriethoxysilane ~PTES! films when irradiated at room temperature with gold ion concentrations of 531014 to 2.531015 cm22 and with carbon ion concentrations of 531015 cm22 were studied using x-ray emission and photoelectron spectroscopies. The fluorescent ultrasoft silicon LII,III and carbon Ka x-ray emission spectra of unirradiated and irradiated PTES films were measured at the Advanced Light Source, and the Center for Advanced Microstructures and Devices. It is found that the PTES polymers that are exposed to ion doses higher than 531014 cm22 convert to Si:O:C ceramics. Annealing the irradiated PTES polymer films at 1000 °C segregates the carbon atoms into sp2-like clusters

Dynamic and static behaviors of CH4 and CO2 in small and large cavities of hydrate

We investigated the static structures and dynamic behaviors for guest molecules (CH4 and CO2) in small and large cavities which are composed of 20 and 24 water molecules, respectively, by B3LYP/6-311++G(d,p) level calculations in GAUSSIAN 09, and using quantum molecular dynamics (QMD) (NVT MD with semiempirical MO PM3 method). For the static calculations, the guest CO2 and CH4 molecules are around at the center of small and large cavities with weak H-bond formations of HOH⋯O 2C and H2O⋯H4C van der Waals interaction systems. Calculated carbon NMR chemical shifts of the CH4 in the gas-state and in the small and large cavities reflected the C-13 experimental tendency, while the calculated carbon NMR chemical shifts of the CO2 in the three states almost correspond to the experimental value in the gas-state. For QMD calculations, we used a cluster model containing 73 water molecules, and examined dynamic behavior of guest molecules in the shell cluster model of 39 water molecules which own small and large cavities. The dynamic behavior of guest molecules are simulated from the trajectory distribution of molecular center of the mass due to the translational motion, and also analyzed using librational motions of guest molecules in the cavities. © 2012 Elsevier B.V. All rights reserved

XPS Spectral Simulation of Chitosan in Thermal Decomposition Process,

金沢大学大学院自然科学研究科物質情報解

Simulation of SIMS for monomer and dimer of lignin under the assumption of thermal decomposition using QMD method,

金沢大学理工研究域物質化学系The thermal decomposition of the monomer and dimer of lignin has been simulated by a quantum molecular dynamics (DMD) method. In the calculation, we controlled the total energy of the system using Nóse-Hoover thermostats in the total energy range of 0.69-0.95 eV, and the sampling position data with a time step of 0.5 fs were carried out up to 3000 (1.5 ps) or 5000 (2.5 ps) steps in ab initio and semiempirical MO methods, respectively. We obtained the thermally decomposed fragments with positive, neutral and negative charges from SCF MO calculation at each data of the last MD step, and simulated the fragment distribution of the monomer and dimer lignins from the last step in 30-40 runs. Simulated mass numbers of positively and negatively charged fragments for lignin monomer and dimer showed considerably good accordance with the experimental results in TOF-SIMS observed by Saito and co-workers. © 2008 Elsevier B.V. All rights reserved