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21.
Ab initio calculations of structures and interaction energies of toluene dimers including CCSD(T) level electron correlation correction 总被引:1,自引:0,他引:1
The intermolecular interaction energy of the toluene dimer has been calculated with the ARS-F model (a model chemistry for the evaluation of intermolecular interaction energy between ARomatic Systems using Feller's method), which was formerly called as the AIMI model III. The CCSD(T) (coupled cluster calculations with single and double substitutions with noniterative triple excitations) interaction energy at the basis set limit has been estimated from the second-order Moller-Plesset perturbation interaction energy at the basis set limit obtained by Feller's method and the CCSD(T) correction term obtained using a medium-size basis set. The cross (C(2)) dimer has the largest (most negative) interaction energy (-4.08 kcal/mol). The antiparallel (C(2h)) and parallel (C(S)) dimers (-3.77 and -3.41 kcal/mol, respectively) are slightly less stable. The dispersion interaction is found to be the major source of attraction in the toluene dimer. The dispersion interaction mainly determines the relative stability of the stacked three dimers. The electrostatic interaction of the stacked three dimers is repulsive. Although the T-shaped and slipped-parallel benzene dimers are nearly isoenergetic, the stacked toluene dimers are substantially more stable than the T-shaped toluene dimer (-2.62 kcal/mol). The large dispersion interaction in the stacked toluene dimers is the cause of their enhanced stability. 相似文献
22.
Bin Wen Seiichi Takami Yoshiyuki Kawazoe Tadafumi Adschiri 《Journal of Physics and Chemistry of Solids》2012,73(11):1264-1267
The mechanical stabilities of K4 carbon and K4-like NaC2 have been studied by performing first-principle calculations. Total energies as functions of isotropic deformations and volume-conserving tetragonal and trigonal deformations have been calculated. For K4 carbon, the total energy shows a minimum for isotropic and trigonal deformations, but exhibits maxima for tetragonal deformation. In contrast, the total energy of K4-like NaC2 shows a minimum under all three deformations. These results indicate that K4 carbon is not a metastable phase, but that K4-like NaC2 is a metastable phase. In addition, the heat of formation of K4-like NaC2 is discussed. 相似文献
23.
Kimitaka Minami Shiori Goto Mehrnoosh Atashfaraz Takanari Togashi Toshihiko Arita Daisuke Hojo Seiichi Takami Tadafumi Adschiri 《Research on Chemical Intermediates》2011,37(2-5):415-419
This paper reports, for the first time, the enhanced dissolution of cellulose in subcritical water by addition of a fatty acid. Simply adding oleic acid dramatically promoted the dissolution of cellulose. High-pressure in-situ observation showed that cellulose dissolved in high-temperature water at approximately 500 K, which is 70 K lower than without oleic acid. The yield of oligo and monosaccharides with oleic acid at 473 K was seven times higher than without oleic acid. 相似文献
24.
Ameneh Sahraneshin Seiichi Takami Kimitaka Minami Daisuke Hojo Toshihiko Arita Tadafumi Adschiri 《Progress in Crystal Growth and Characterization of Materials》2012,58(1):43-50
Organic-functionalized nanoscale yttrium aluminum garnet (YAG) particles were synthesized via a simple rapid supercritical hydrothermal method in the presence of oleylamine and oleic acid as organic surface modifiers. The presence of the organic molecules resulted in the various morphologies of the produced YAG particles, including cubic, spherical and chainlike structures. Because of their hydrophobic surface character, as-synthesized particles were dispersible in organic solvents. 相似文献
25.
Katsuhito Suzuki Akihiro Sato Hiroaki Okumura Tadafumi Hashimoto Antonio Norio Nakagaito Hiroyuki Yano 《Cellulose (London, England)》2014,21(1):507-518
Novel high-strength, micro-fibrillated cellulose (MFC)-reinforced polypropylene (PP) composites were prepared using maleic anhydride polypropylene (MAPP) and a cationic polymer having a primary amino group (CPPA) as coupling agents. Un-dried kraft pulp was micro-fibrillated into nano- to submicron-wide fibrils by kneading with powdered PP and the coupling agents via a twin-screw extruder. The composites were prepared by injection molding. The MFC-reinforced PP composites containing both coupling agents MAPP and CPPA (combination system) showed extremely high mechanical strength compared with the MFC-reinforced composite containing only MAPP. The tensile strength of a 30 wt% MFC-PP composite containing the combination system was 27 % higher than that of the composite containing only MAPP, and more than 60 % higher than that of neat PP. In addition, the heat distortion temperature, under a 1.82-MPa flexural load, of the composite with the combination system was 17 °C higher than that of the composite with MAPP only, and 34 °C higher than that of neat PP. The anisotropy of the modulus and strength in the injection-molded MFC composites was lower than that of glass fiber-reinforced PP. 相似文献
26.
Shingo Urata Tadafumi Uchimaru Asit K. Chandra Akira Takada Akira Sekiya 《国际化学动力学杂志》2002,34(9):524-530
Density functional theory was used to estimate the lifetime of fluorinated formates, which are primary products from the oxidation of hydrofluoroethers. First, the C? H bond dissociation enthalpies (BDEs) of 10 fluorinated formates, CnF2n + 1OC(O)H (n = 1–4) and CnHF2nOC(O)H (n = 1–3) have been calculated by using the density functional theory with (RO)B3LYP/6‐311G(d,p). Secondly, from these computed BDEs, the rate constants kOH of the hydrogen abstraction reaction between the fluorinated formates and OH radicals have been estimated using the formulation proposed by Heicklen (Int. J. Chem. Kinet. 13 , 651, 1981). We modified the formulation proposed by Heicklen in order to relate BDEs to kOH for formates based on the results of the ab initio studies using standard transition state theory with the G2(MP2) level. Consequently, the kOH of all the formates considered here are estimated to be around 1.5–4.7 × 10?14 cm3 molecule?1 s?1 at 298 K. Their lifetimes concerning with the decomposition by OH radicals (τOH) in atmosphere have been evaluated as 0.4–4.5 years from the estimated kOH. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 524–530, 2002 相似文献
27.
Yoshiro Kobayashi Takeo Taguchi Tadafumi Terada Jun-ichi Oshida Masuo Morisaki Nobuo Ikekawa 《Tetrahedron letters》1979,20(22):2023-2026
From cholenic acid 24,24-difluoro-25-hydroxyvitamin D3 and 24ξ-fluoro-25-hydroxyvitamin D3 were prepared. 相似文献
28.
Tsuzuki S Honda K Fujii A Uchimaru T Mikami M 《Physical chemistry chemical physics : PCCP》2008,10(19):2860-2865
Geometries and interaction energies for methane clusters with naphthalene and pyrene were studied. Estimated CCSD(T) interaction energies for the clusters at the basis set limit were -1.92 and -2.50 kcal mol(-1), respectively. Dispersion is mainly responsible for the attraction. Electrostatic interaction is very small. Although the benzene-methane cluster prefers a monodentate structure, in which a C-H bond of the methane points toward the benzene, the methane clusters with the polycyclic aromatic hydrocarbons do not prefer monodentate structures. In the benzene-methane cluster, the weak electrostatic interaction stabilizes the monodentate structure. On the other hand the dispersion interaction controls the orientation of methane in the naphthalene and pyrene clusters. The dispersion interactions in these clusters are significantly larger than those in the benzene-methane cluster. The methane prefers the orientation which is suitable for stabilization by dispersion. Hydrogen atoms of the methane locate above the centers of hexagonal rings of the polycyclic aromatic hydrocarbons in the stable structures. The structures have a small steric repulsion and this positions them only a short distance from the aromatic plane. The large dispersion contribution to the attraction shows that interactions between carbon atoms are mainly responsible for the attraction, and that hydrogen atoms are not important for the attraction. This shows that the interactions between the methane and polycyclic aromatic hydrocarbons are not pi-hydrogen bonds. 相似文献
29.
Elim HI Cai B Sugihara O Kaino T Adschiri T 《Physical chemistry chemical physics : PCCP》2011,13(10):4470-4475
We have experimentally carried out a Rayleigh scattering study of a high refractive index TiO(2) nanohybrid polymer. By employing the Rayleigh scattering technique with at least three different wavelengths, we can obtain the Rayleigh ratio of the TiO(2) nanohybrid polymer at each utilized wavelength. These measured Rayleigh ratios are then used to estimate the size of the nanoparticle and determine the number of nanoparticles per unit volume or particle density. Furthermore, this technique can be used to evaluate the dominant size of nanoparticles in the nanohybrid polymer mainly contributed to Rayleigh scattering. 相似文献
30.
Zbignew Pawelka Asit K Chandra Tadafumi Uchimaru Thérèse Zeegers-Huyskens 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(1):17-31
The conformation and vibrational properties of 2-methoxy-1,2-diphenylethanone (MDPE) are investigated in the gas phase and in organic solvents. Ab initio calculations carried out at the B3LYP/6-31G(d) level demonstrate that three stable conformers having cisoid, skewed and transoid structures are present in the gas phase. In the gas phase, the conformers are separated by a low energy barrier and their relative energies do not differ by more than 7.2 kJ mol (-1) Like in crystalline MDPE 'Acta Crystallogr. Sect. C 44 (1988) 894', weak CH...O hydrogen bonds are present in the cisoid conformation. The IR and Raman spectra of solid MDPE are discussed. Several vibrational modes are split in organic solvents. A comparison between the theoretical data and the experimental dipole moments indicates that two conformers are present in solution, the population of the cisoid form increasing with the permittivity of the medium. 相似文献