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First-Principles Study of Structural,Elastic and Electronic Properties of OsSi

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Communications in Theoretical Physics 2009年第10期52卷 701-706页

作者： LI Jin LINGHU Rong-Feng yang Ze-Jin CAO yang yang xiang-dong Institute of Atomic and Molecular Physics of Sichuan University Chengdu 610065 China College of Material and Chemical Engineering Hainan University Haikou 570228 China Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti Resources Haikou 570228 China School of Physics and Electronic Science Guizhou Normal University Guiyang 550001 China

First-principles study of structural, elastic, and electronic properties of the B20 structure OsSi has been reported using the plane-wave pseudopotential density functional theory method. The calculated equilibrium lattice and elastic constants are in good agreement with the experimented data and other theoretical results. The dependence of the elastic constants, the aggregate elastic modulus, the deviation from the Cauchy relation, the elastic wave velocities in different directions and the elastic anisotropy on pressure have been obtained and discussed. This could be the first quantitative theoretical prediction of the elastic properties under high pressure of OsSi compound. Moreover, the electronic structure calculations show that OsSi is a degenerate semiconductor with the gap value of 0.68 eV, which is higher than the experimental value of 0.26 eV. The analysis of the PDOS reveals that hybridization between Os d and Sip states indicates a certain covalency of the Os-Si bonds.

关键词： OsSi elastic constants electronic properties high pressure effect

Isotope Effect in Collision Between Helium Atom and Hydrogen Molecule

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Chinese Physics Letters 1998年第1期15卷 19-20页

作者： yang xiang-dong ZHANG Ji-yan JlNG Fu-qian Laboratory for Shock Wave and Detonation Physics Research Southwest Institute of Fluid PhysicsP.O.Box 523Chengdu 610003 Institute of Atomic and Molecular Science under High Temperature and High Pressure Sichuan Union UniversityChengdu 610065

Rotationally inelastic He-H_(2),D_(2),T_(2) collision was studied *** cross sections were calculated by using the close coupling method for relative kinetic energies of 0.01 to 0.54 ***-Oppenheimer approximation was employed to determine the potential surface of He-D_(2),He-T_(2),and He-H_(2).Careful comparison between the cross sections of the isotopically substituted systems was carried out,and the regular changes of the total cross sections of the isotopically substituted He-H_(2) colliding systems were obtained.

关键词： substituted collision cross

Application of PCA and HCA to the Structure-activity Relationship(SAR) Study of Fluoroquinolones

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Chinese Journal of Structural Chemistry 2006年第11期25卷 1351-1358页

作者： LI Xiao-Hong ZHANG Rui-Zhou CHENG Xin-Lu yang xiang-dong Institute of Atom and Molecular Physics Sichuan University Chengdu 610065 China Xinxiang Teacher＇s College Xinxiang 453000 China

Density functional theory （DFT） was used to calculate a set of molecular descri ptors （properties） for 14 fluoroquinolones with *** activity. Principal component analysis （PCA） and hierarchical cluster analysis （HCA） were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying fluoroquinolones according to their *** activity degree. The PCA shows that the variables of ELUMO, AEHL, μ, Q2, Q3, Q5, Q6, QB, LogP, MR and MP are responsible for the separation between compounds with higher and lower *** activities. The HCA results are similar to those obtained with PCA. By using the chemometric results, 4 synthetic compounds were analyzed through PCA and HCA, and 2 of them are proposed as active molecules against ***, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with *** activity.

关键词： structure-activity relationship DFT PCA HCA

Quantitative Structure-activity Relationship of TIBO HIV-1 Inhibitors

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Chinese Journal of Structural Chemistry 2007年第8期26卷 889-896页

作者： LI Xiao-Hong ZHANG Rui-Zhou CHENG Xin-Lu yang xiang-dong College of Science Henan University of Science and Technology Luoyang 471003 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

Density functional theory （DFT） was used to calculate a set of molecular descriptors （properties） for 14 TIBO derivatives with anti-HIV activity. Principal component analysis （PCA） and hierarchical cluster analysis （HCA） were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying TIBO derivatives according to their degree of anti-HIV activity. The PCA showed that the EHOMO, μ, LogP, QA, QB and MR variables are responsible for the separation between compounds with higher and lower anti-HIV activity. The HCA results are similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA and three of them are proposed as active molecules against HIV, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new TIBO derivatives with anti-HIV activity. The model obtained showed not only statistical significance but also predictive ability.

关键词： structure-activity relationship DFT PCA HCA

Orbital responses to methyl sites in C_nH_(2n+2) (n=1-6)

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Chinese Physics B 2012年第2期21卷 16-22页

作者： yang Ze-Jin Cheng Xin-Lu Zhu Zhen-He yang xiang-dong School of Science Zhejiang University of TechnologyHangzhou 310023China Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610065China

Orbital responses to methyl sites in CnH2n＋2 （n = 1-6） are studied by B3LYP/TZVP based on the most stable geometries using the B3LYP/aug-cc-pVTZ method. Vertical ionization energies are produced using the SAOP/et-pVQZ model for the complete valence space. The highest occupied molecular orbital （HOMO） investigations indicate the p- electron profiles in methane, ethane, propane, and n-butane. By increasing the number of carbon-carbon bonds in lower momentum regions, the s, p-hybridized orbitals are built and display strong exchange and correlation interactions in lower momentum space （P 〈 0.50 a.u.）. Meanwhile, the relative intensities of the isomers in lower momentum space show the strong bonding number dependence of the carbon-carbon bonds, meaning that more electrons have contributed to orbital construction. The study of representative valence orbital momentum distribution further confirms that the structural changes lead to evident electronic rearrangement over the whole valence space. An analysis based on the isomers reveals that the valence orbitals are isomer-dependent and the valence ionization energy experiences an apparent shift in the inner valence space. However, such shifts are greatly reduced in the outer valence space. Meanwhile, the opposite energy shift trend is found in the intermediate valence space.

关键词： electron momentum spectroscopy valence ionization energy charge density distribution

The influence of isotope substitution of neon atom on the integral cross sections of rotational excitation in Ne-Na2 collisions

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Chinese Physics B 2011年第2期20卷 1-6页

作者： Zang Hua-Ping Li Wen-Feng Linghu Rong-Feng Cheng Xin-Lu yang xiang-dong Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China School of Physics and Electronic Science Guizhou Normal University Guiyang 550001 China

This paper applies the multiple ellipsoid model to the 16Ne （20Ne, 28Ne, 34Ne）-Na2 collision systems, and calcu- lates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces. Moreover, by analysing the differences of these integral cross sections, it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number j＇, and with the change of the mass of isotope substitution neon atom. Finally, the contribution of different regions of the potential to inelastic cross sections for 20Ne-Na2 collision system is investigated at relative incident energy of 190 meV.

关键词： multiple hard-ellipsoid model Ne isotopic atoms integral cross sections ellipsoid equipotential surface

High Temperature Spectrum for v3 Band of Carbon Dioxide

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Communications in Theoretical Physics 2007年第5期47卷 892-896页

作者： SONG Xiao-Shu yang xiang-dong GUO Yun-dong WANG Jun CHENG Xin-Lu LING-HURong-Feng Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China School of Physics and Chemistry Guizhou Normal University Guiyang 550001 China

The total internal partition sums （TIPS） are calculated at the temperature up to 6000 K for 12 C16 02. Using the calculated partition functions, we produce the line intensities of v3 band of 12C1602 at several high temperatures. The results show that the calculated line intensities are in very good agreement with those of HITRAN database at the temperature up to 3000 K, which provides a strong support for the calculations of TIPS and line intensities at high temperature. Then the calculation is extended to further high temperature, and the simulated spectra of u3 band of 12C1602 at 5000 and 6000 K are reported.

关键词： partition functions carbon dioxide line intensities high temperature

Phonon density of states and phonon dispersion of superconducting MgB2

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原子与分子物理学报 2006年第B4期23卷 241-245页

作者： GUO Yun-dong CAI Da-feng ZHOU Li-ping CHEN xiang - rong yang xiang-dong Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 P. R. China Department of Physics Neijiang Teacher＇s College Neijiang 641112 P. R. ehina International Centre for Materials Physics Chinese Academy of Seiences Shenyang 110016 P. R. China

For the superconductor MgB2, we have calculated the phonon density of states (DOS), phonon dispersion and Eliashberg function throughout the Brillouin zone (BZ), using an empirical potential model. The calculated values are consistent with the theoretical and experimental values. The calculated results show our empirical potential model is available for MgB2.

关键词： MgB2 声子密度态经验位势模型超导体声子散射

Study on High-Temperature Spectra of Asymptotic Asymmetric-Top Molecule O_3

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Communications in Theoretical Physics 2008年第8期50卷 481-485页

作者： SONG Xiao-Shu GUO Yun-dong LING-HU Rong-Feng Lv Bing CHENG Xin-Lu yang xiang-dong School of Physics and Chemistry Guizhou Normal University Guiyang 550001 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China Department of Physics Neijiang Teacher＇s College Neijiang 641112 China

The line intensities of 001-000 transition of the asymptotic asymmetric-top Oa molecule at several temperatures are calculated by directly calculating the partition functions and regarding the rotationless transition dipole moment squared as a constant. The calculated values of the total internM partition sums （TIPS） are consistent with the data of HITRAN database with -0.61% at 296 K. The calculated line intensity data at 500 K and 3000 K are also in excellent agreement with the data in HITRAN database with less than 0.659% and 5.458% at 500 K and 3000 K, which provide a strong support for the calculations of partition function and fine intensity at high temperature. Then we extend the calculation to higher temperatures. The line intensities and simulated spectra of v3 band of the asymptotic asymmetric-top O3 molecule at 4000 and 5000 K are reported. The results are of significance for the studying of the molecular high-temperature spectrum including experimental measurements and theoretical calculations.

关键词： asymptotic asymmetric-top molecule line intensities partition functions high temperature spectrum