By utilizing phase field method combined with analysis on free energy and interatomic potentials, pre-precipitation phase formation and transformation process of Ni0.75Al0.05Fe0.2 alloy in early precipitation stage du...By utilizing phase field method combined with analysis on free energy and interatomic potentials, pre-precipitation phase formation and transformation process of Ni0.75Al0.05Fe0.2 alloy in early precipitation stage during the ageing process under 1 000 K were studied. And free energy, microstructures, compositions and volume fractions of pre-precipitation phase and equilibrium phase were analyzed. The simulation results indicate that nonstoichiometric Llo pre-precipitation phase formed first, and then would gradually transform into L12 equilibrium phase. It is discovered that the phase transformation process was closely related to free energy and interatomic potentials. Additionally, it is revealed that free energy of Llo pre-precipitation phase was higher and interatomic potential was smaller than that of L12 equilibrium phase. Therefore, it is concluded that Llo phase was unstable, and phase transformation would occur to L12 which was more stable.展开更多
According to the basic information of sequences of Ti and Al characteristic atoms in hcp Ti-Al system, the compositional variations of the electronic structure, atomic potential energies, atomic volumes, lattice const...According to the basic information of sequences of Ti and Al characteristic atoms in hcp Ti-Al system, the compositional variations of the electronic structure, atomic potential energies, atomic volumes, lattice constants and cohesive energies of the ordered hcp Ti3Al type alloys were calculated by the framework of systematic science of alloys(SSA). The electronic structure of the hcp Ti3Al compound consisted of ψ 4Thiand ψ 0Ahl atoms is 0.75[Ar] (3dn)0.573(3dc)2.1685(4sc)0.972(4sf)0.3093+0.25[Ne](3sc)1.32· (3pc)1.19(3sf)0.49. The factors of controlling lattice stability are electronic structure, atomic energies and atomic concentration. The Ti ψ 4hatoms play a determinative role in forming D019 structure with a=0.287 2 nm, c=0.456 4 nm, atomic cohesive energy ε=4.810 8 eV/atom and heat of formation △H=-0.332 8 eV/atom. These calculated values are in good agreement with experimental values (a=0.287 5 nm, c=0.46 0 nm, △H=-0.27, -0.29 eV/atom). The calculated cohesive energy of the hcp Ti3Al compound is slightly bigger than that of the fcc Ti3Al.This is a good sign that makes it feasible to stabilized L12 structure of the hcp Ti3Al compound by ternary element. The new element should have more dc-electrons than Ti-metal and occupy at the Ti-lattice points.展开更多
The first-order revision and the approximation analytical formula of the energy levels for hydrogen-like atoms under the condition of Debye shielding potential are achieved by means of the Rayleigh–Schr?dinger pertur...The first-order revision and the approximation analytical formula of the energy levels for hydrogen-like atoms under the condition of Debye shielding potential are achieved by means of the Rayleigh–Schr?dinger perturbation theory; meanwhile, the corresponding recurrence relations are obtained from the use of the solution of power series. Based on the above solutions and with the use of energy consistent method the equivalent value of second-order reversion under the condition of Debye shielding potential is produced as well and the result is compared with the data obtained by the numerical method. Besides, the critical bond-state and corresponding cut-off conditions are discussed.展开更多
The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of...The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other： in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions.展开更多
The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction o...The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction of O（^1D） and C2H5Cl produces two energy-rich intermediates, IM1 and IM2, which subsequently decompose into various products. The calculations of the branching ratios of various products formed through the two intermediates were carried out using RRKM （Rice-Ramsperger-Kassel-Marcus） theory at the collision energies of 0, 20.9, 41.8, 62.7, 83.6, 104.5, and 125.4 kJ/mol. HCl is the main decomposition product for IM1; CH2OH is the main decomposition product for IM2. Since IM1 is more stable than IM2, HCl is probably the main product of the O（^1D）＋C2H5Cl reaction.展开更多
The limit of rotational energy transfer in atom-diatomic systems due to inelastic collision was investigated over the wide range of collision energy, reduced mass and potential parameters of F2-He system. The IICS （i...The limit of rotational energy transfer in atom-diatomic systems due to inelastic collision was investigated over the wide range of collision energy, reduced mass and potential parameters of F2-He system. The IICS （integral inelastic cross-sections） is obtained by the IOSAM （infinite order sudden approximation method） and predicted by PG （power-gap） law in the variation of cross-sections. The investigation provided that the classical limit of angular momentum transfer is given by hard ellipsoid potential is meaningful even the cross-sections computed on the real potential, provided the classical turning point on the surface of soft potential is assumed as hard potential surface.展开更多
基金Projects(10902086, 50941020, 50875217) supported by the National Natural Science Foundation of China Projects(JC201005) supported by Basic Research Fund of Northwestern Polytechnical University, China Project supported by Graduate Starting Seed Fund and Doctoral Foundation of Northwestern Polytechnical University, China
文摘By utilizing phase field method combined with analysis on free energy and interatomic potentials, pre-precipitation phase formation and transformation process of Ni0.75Al0.05Fe0.2 alloy in early precipitation stage during the ageing process under 1 000 K were studied. And free energy, microstructures, compositions and volume fractions of pre-precipitation phase and equilibrium phase were analyzed. The simulation results indicate that nonstoichiometric Llo pre-precipitation phase formed first, and then would gradually transform into L12 equilibrium phase. It is discovered that the phase transformation process was closely related to free energy and interatomic potentials. Additionally, it is revealed that free energy of Llo pre-precipitation phase was higher and interatomic potential was smaller than that of L12 equilibrium phase. Therefore, it is concluded that Llo phase was unstable, and phase transformation would occur to L12 which was more stable.
基金Project(50471058) supported by the National Natural Science Foundation of ChinaProject(06FJ3133) supported by the Natural Science Foundation of Hunan Province, China
文摘According to the basic information of sequences of Ti and Al characteristic atoms in hcp Ti-Al system, the compositional variations of the electronic structure, atomic potential energies, atomic volumes, lattice constants and cohesive energies of the ordered hcp Ti3Al type alloys were calculated by the framework of systematic science of alloys(SSA). The electronic structure of the hcp Ti3Al compound consisted of ψ 4Thiand ψ 0Ahl atoms is 0.75[Ar] (3dn)0.573(3dc)2.1685(4sc)0.972(4sf)0.3093+0.25[Ne](3sc)1.32· (3pc)1.19(3sf)0.49. The factors of controlling lattice stability are electronic structure, atomic energies and atomic concentration. The Ti ψ 4hatoms play a determinative role in forming D019 structure with a=0.287 2 nm, c=0.456 4 nm, atomic cohesive energy ε=4.810 8 eV/atom and heat of formation △H=-0.332 8 eV/atom. These calculated values are in good agreement with experimental values (a=0.287 5 nm, c=0.46 0 nm, △H=-0.27, -0.29 eV/atom). The calculated cohesive energy of the hcp Ti3Al compound is slightly bigger than that of the fcc Ti3Al.This is a good sign that makes it feasible to stabilized L12 structure of the hcp Ti3Al compound by ternary element. The new element should have more dc-electrons than Ti-metal and occupy at the Ti-lattice points.
文摘The first-order revision and the approximation analytical formula of the energy levels for hydrogen-like atoms under the condition of Debye shielding potential are achieved by means of the Rayleigh–Schr?dinger perturbation theory; meanwhile, the corresponding recurrence relations are obtained from the use of the solution of power series. Based on the above solutions and with the use of energy consistent method the equivalent value of second-order reversion under the condition of Debye shielding potential is produced as well and the result is compared with the data obtained by the numerical method. Besides, the critical bond-state and corresponding cut-off conditions are discussed.
基金The project supported by National Natural Science Foundation of China under Grant No.10475021
文摘The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other： in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions.
基金ACKNOWLEDGMENT This work was supported Science Foundation of China by the National Natural （No.50772107）.
文摘The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction of O（^1D） and C2H5Cl produces two energy-rich intermediates, IM1 and IM2, which subsequently decompose into various products. The calculations of the branching ratios of various products formed through the two intermediates were carried out using RRKM （Rice-Ramsperger-Kassel-Marcus） theory at the collision energies of 0, 20.9, 41.8, 62.7, 83.6, 104.5, and 125.4 kJ/mol. HCl is the main decomposition product for IM1; CH2OH is the main decomposition product for IM2. Since IM1 is more stable than IM2, HCl is probably the main product of the O（^1D）＋C2H5Cl reaction.
文摘The limit of rotational energy transfer in atom-diatomic systems due to inelastic collision was investigated over the wide range of collision energy, reduced mass and potential parameters of F2-He system. The IICS （integral inelastic cross-sections） is obtained by the IOSAM （infinite order sudden approximation method） and predicted by PG （power-gap） law in the variation of cross-sections. The investigation provided that the classical limit of angular momentum transfer is given by hard ellipsoid potential is meaningful even the cross-sections computed on the real potential, provided the classical turning point on the surface of soft potential is assumed as hard potential surface.
