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181.
The transcorrelated (TC) method is one of the promising wave-function-based approaches for the first-principles electronic structure calculations. In this method, the many-body wave function is approximated as the Jastrow-Slater type and one-electron orbitals in the Slater determinant are optimized with a one-body self-consistent-field equation such as that in the Hartree-Fock (HF) method. Although the TC method has yielded good results for both molecules and solids, its computational cost in solid-state calculations, being of order O(N(k)(3)N(b)(3)) with N(k) and N(b) the respective numbers of k-points and bands, has for some years hindered its wide application in condensed matter physics. Although an efficient algorithm was proposed for a Gaussian basis set, that algorithm is not applicable to a plane-wave basis that is suited to and widely used in solid-state calculations. In this paper, we present a new efficient algorithm of the TC method for the plane-wave basis or an arbitrary basis function set expanded in terms of plane waves, with which the computational cost of the TC method scales as O(N(k)(2)N(b) (2)). This is the same as that of the HF method. We applied the TC method with the new algorithm to obtain converged band structure and cell parameters of some semiconductors. 相似文献
182.
Takashi Sakuma Saumya R. Mohapatra Hiroyuki Uehara Khairul Basar Osamu Kamishima 《Journal of Non》2011,357(2):559-562
Neutron diffraction measurements have been performed on powder Ge at 6, 150 and 300 K. Oscillatory diffuse scattering intensity is clearly observed at 150 and 300 K. The diffuse scattering theory including correlation effects among thermal displacements of atoms is applied to background function in the Rietveld analysis. The inter-atomic distance and temperature dependence of the values of correlation effects are discussed. The force constants among the first, second and third nearest neighboring atoms in Ge are obtained from the values of correlation effects and Debye-Waller temperature parameters. A phonon dispersion spectrum in Λ [111] direction for Ge crystal has also been calculated at 80 K using inter-atomic force constants and the crystal structure. 相似文献
183.
Naruki M Fukao Y Funahashi H Ishino M Kanda H Kitaguchi M Mihara S Miwa K Miyashita T Murakami T Nakura T Sakuma F Togawa M Yamada S Yoshimura Y En'yo H Muto R Tabaru T Yokkaichi S Chiba J Ieiri M Sasaki O Sekimoto M Tanaka KH Hamagaki H Ozawa K 《Physical review letters》2006,96(9):092301
The invariant mass spectra of e+e- pairs produced in 12 GeV proton-induced nuclear reactions are measured at the KEK Proton Synchrotron. On the low-mass side of the meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted. 相似文献
184.
Kubota Y Haraguchi K Kunikata M Hayashi M Ohkawa M Tanaka H 《The Journal of organic chemistry》2006,71(3):1099-1103
Upon epoxidation with dimethyldioxirane, the 2',5'-bis-O-silyl derivatives of 9-(3-deoxy-beta-D-glycero-pent-3-enofuranosyl)adenine gave the respective "3',4'-up" epoxides exclusively. Reaction between these epoxides and Me3Al was investigated in detail. It was found that the stereoselectivity of epoxide ring opening (anti versus syn) varied significantly upon changing the amount of Me3Al, the solvent, the O-silyl protecting group, and the reaction temperature. A possible reaction mechanism is proposed. 相似文献
185.
Masayuki Ogawa Jyunichi Koyanagi Katsuya Sakuma Akira Tanaka Katsumi Yamamoto 《Journal of heterocyclic chemistry》1999,36(3):819-822
The reaction of methyl 5-(2-isocyanatophenylthio)-2-furancarboxylate 2 with N-methylpiperazine gave 5-(2-N-piperazinocarbamoylphenylthio)-2-furancarboxylate 3a . Furthermore, 4-N-methylpiperazinyl-2-methoxycarbonylfuro[2,3-b][1,5]benzothiazepine 4a was obtained by the Bischler-Napieralski reaction of 3a with phosphorus oxychloride in the present of phosphorus pentoxide. Three furobenzothiazepines could be obtained using the same method. Based on the pharmacological studies of these compounds, it was found that 4-morpholinyl-2-methoxycarbonylfuro[2,3-b][1,5]benzothiazepine 4b had anti-inflammatory activity similar to flufenamic acid. 相似文献