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Formation Mechanism and Binding Energy for Body-Centred Regular Tetrahedral Structure of Li5

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Communications in Theoretical Physics 2006年第5期45卷 914-918页

作者： LI Ping YANG Jian-Hui gou qing-quan Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

The formation mechanism for the body-centred regular tetrahedral structure of Li5 cluster is proposed. The curve of the total energy versus the separation R between the nucleus at the centre and nuclei at the apexes for this structure of Li5 has been calculated by using the method of gou＇s modified arrangement channel quantum mechanics （MACQM）, The result shows that the curve has a minimal energy of-37.2562 a.u. at R =14.5α0. When R approaches infinity the total energy of five lithium atoms has the value of-37.1401 a.u. So the binding energy of Li5 with respect to five lithium atoms is the difference of 0.1161 a.u. for the above two energy values. Therefore the binding energy per atom for Li5 is 0.023 22 a.u., or 0.632 eV, which is greater than the binding energy per atom of 0.453 eV for Li2 and the binding energy per atom of 0.494 eV for Li3 calculated previously by us. This means that the Li3 cluster may be formed stably in a body-centred regular tetrahedral structure with a greater binding energy.

关键词： Li5 cluster formation mechanism binding energy

Formation Mechanism and Binding Energy for Equilateral Triangle Structure of Li3 Cluster

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Communications in Theoretical Physics 2005年第3X期44卷 525-528页

作者： YANG Jian-Hui LI Ping gou qing-quan Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

The formation mechanism for the equilateral triangle structure of Lia cluster is proposed. The curve of the total energy versus the interatomic distance for this structure has been calculated by using the method of gou＇s Modified Arrangement Channel quantum Mechanics. The result shows that the curve has a minimal energy of-22.338 60 a.u at R = 5.82 ao. The total energy of Lia when R approaches co has the value of-22.284 09 a.u. This is also the total energy of three lithium atoms dissociated from Lia. The difference value of 0.0545 08 a.u. for the above two energy values is the dissociation energy of Li3 cluster, which is also its binding energy. Therefore the binding energy per lithium atom for Lia is 0.018 169 a.u. = 0.494 eV, which is greater than the binding energy of 0.453 eV per atom for Li2 calculated in a previous work. This means that the Li3 cluster may be formed in the equilateral triangle structure of side length R = 5.82ao stably with a stronger binding from the symmetrical interaction among the three lithium atoms.

关键词： Li3 cluster binding energy equilateral triangle structure

Formation Mechanism and Binding Energy for Equilateral Triangle Structure of He3+ Cluster

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Communications in Theoretical Physics 2002年第5期38卷 597-600页

作者： gou qing-quan ZHANG Jian-Ping LI Ping Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China Department of Physics Leshan Teacher's College Leshan 614000 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

The formation mechanism for the equilateral triangle structure of the He3+ cluster is proposed. The curveof the total energy versus the internuclear distance R for this structure has been calculated by the method of a modifiedarrangement channel quantum mechanics. The result shows that the curve has a minimal -7.81373 a.u at 1 = 1.55 *** binding energy of He3+ with respect to He+He+ +He was calculated to be 0.1064 a.u. (about 2.89 eV). This meansthat the He3+ cluster may be formed in the equilateral triangle structure stably by the interaction of He+ with two heliumatoms.

关键词： He3+ cluster, binding energy, equilateral triangle structure

Formation Mechanism and Binding Energy for Regular Tetrahedral Structure of Li4

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Communications in Theoretical Physics 2006年第5X期46卷 914-918页

作者： gou qing-quan YANG Jian-Hui LI Ping Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China

The formation mechanism for the regular tetrahedral structure of Li4 cluster is proposed. The curve of the total energy versus the separation R between the two nuclei has been calculated by using the method of gou＇s modified arrangement channel quantum mechanics （MACQM）. The result shows that the curve has a minimal energy of-29.8279 a.u. at R = 14.50 ao. When R approaches infinity the total energy of four lithium atoms has the value of-29.7121 a.u. So the binding energy of Li4 with respect to four lithium atoms is the difference of 0.1158 *** the above two energy values. Therefore the binding energy per atom for Lh is 0.020 a.u., or 0.7878 eV, which is greater than the binding energy per atom of 0.453 eV for Li2, the binding energy per atom of 0.494 eV for Lia and the binding energy per atom of 0.632 eV for Li5 calculated previously by us. This means that the Li4 cluster may be formed stably in a regular tetrahedral structure of side length R = 14.50 ao with a greater binding energy.

关键词： Li4 cluster formation mechanism binding energy

Elastic and Thermodynamic Properties of CdSe from First-Principles Calculations

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Communications in Theoretical Physics 2008年第7期50卷 220-226页

作者： TAN Jia-Jin CHENG Yan ZHU Wen-Jun gou qing-quan College of Physical Science and Technology Sichuan University Chengdu 610064 China Laboratory for Shock Wave and Detonation Physics Research Instituteof Fluid Physics Chinese Academy of Engineering Physics Mianyang 621900 China

The lattice parameters, bulk modulus, phase transition pressure, and temperature dependencies of the elastic constants cij of CdSe are investigated by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of Density Functional Theory （DFT）. It is found that the phase transitions from the ZB structure to the RS structure and from WZ structure to RS structure are 2.2 GPa and 2.8 GPa, respectively. Our results agree well with the available experimental data and other theoretical results. The aggregate elastic modulus （B, G, E, A ）, the Poisson＇s ratio （v）, the Griuneisen parameter （γ）, the Debye temperature θD on pressure and temperature are also successfully obtained.

关键词： elastic properties thermodynamic properties density functional theory CdSe

Shell Model for Elastic and Thermodynamic Properties of Gallium Nitride with Hexagonal Wurtzite Structure

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Communications in Theoretical Physics 2008年第12期50卷 1443-1448页

作者： CHENG Yan TU Ya-Jing ZENG Zhao-Yi gou qing-quan College of Physical Science and Technology Sichuan University Chengdu 610064 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China School of Computer Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

Shell model molecular dynamic simulation with interatomic pair potential is utilized to investigate the elastic and thermodynamic properties of gallium nitride with hexagonal wurtzite structure （w-GaN） at high pressure. The calculated elastic constants Cij at zero pressure and 300 K agree well with the experimental data and other calculated values. Meanwhile, the dependences of the relative volume V/Vo, elastic constants Cij, entropy S, enthalpy H, and heat capacities Cv and Up on pressure are successfully obtained. From the elastic constants obtained, we also calculate the shear modulus G, bulk modulus B, Young＇s modulus E, Poisson＇s ratio v, Debye temperature ΘD, and shear anisotropic factor Ashear on pressures.

关键词： shell model molecular dynamics elastic properties thermodynamic properties GaN

Theoretical Calculations for Structural, Elastic and Thermodynamic Properties of MgB2 under High Pressure

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Communications in Theoretical Physics 2006年第3期45卷 558-564页

作者： WANG Hai-Yan CHENG Yan CHEN Xiang-Rong gou qing-quan Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China College of Physical Science and Technology Sichuan University Chengdu 610064 China International Centre for Materials Physics the Chinese Academy of Sciences Shenyang 110016 China

We have investigated the structural and elastic properties of MgB2 under high pressures using the full- potential linearized muffin-tin orbital （FP-LMTO） scheme within the generalized gradient approximation correction （GGA） in the frame of density functional theory. The calculated pressure dependence of the normalized volume is in excellent agreement with the experimental results. At the same time the elastic constants and acoustic anisotropy as a function of applied pressure are presented. Through the quasi-harmonic Debye model, we also investigate the thermodynamic properties of MgB2.

关键词： elastic constants thermodynamic properties full-potential linearized muffin-tin orbital MgB2

Electronic and Optical Properties of Rock-Salt A1N under High Pressure via First-Principles Analysis

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Communications in Theoretical Physics 2008年第10期50卷 990-994页

作者： ZHANG Wei CHEN Xiang-Rong CAI Ling-Cang gou qing-quan Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics Mianyang 621900 China

Electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis *** of band structures suggests that the rock-salt AIN has an indirectgap of 4.53 eV,which is in good agreement with other *** investigating the effects of pressure on the energygap,the different movement of conduction band at X point below and above 22.5 GPa is *** opticalproperties including dielectric function,absorption,reflectivity,and refractive index are also calculated and *** found that the rock-salt AIN is transparent from the partially ultra-violet to the visible light area and hardly does thetransparence affected by the ***,the curve of optical spectrum will shift to high energy area (blueshift) with increasing pressure.

关键词： semiconductors electronic band structure optical properties density functional theory

First-Principle Calculations for Transition Phase and Elastic Properties of SrS

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Communications in Theoretical Physics 2008年第6期49卷 1611-1614页

作者： CHENG Yan LU Lai-Yu JIA Ou-He gou qing-quan School of Physical Science and Technology Sichuan University Chengdu 610064 China Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics Mianyang 621900 China

The transition phase and elastic properties of SrS from NaCl structure （B1） to CsCl structure （B2） are investigated by ab initio plane-wave pseudopotential density functional theory method and by the quasi-harmonic Debye model. The transition pressure varies non-linearly with temperature, and the pressure of the mechanical instability increases linearly with increasing temperature. It is shown that the B1 structure SrS is a most elastically anisotropic minerat any pressure. The Debye temperature, the heat capacity, thermal expansion and Gruneisen parameter over a wide range of pressures and temperatures are also obtained.

关键词： elastic constants generalized gradient approximation quasi-harmonic Debye model SrS