Two-electron atoms have been investigated near threshold of double escape within the framework of hyperspherical coordinates. A particularly useful set of hyperspherical angles has been used. It is well known for many...Two-electron atoms have been investigated near threshold of double escape within the framework of hyperspherical coordinates. A particularly useful set of hyperspherical angles has been used. It is well known for many years that the hyperradial motion is nearly separable from the hyperspherical angular motion. Therefore, the Born-Oppenheimer separation method should be useful. However, the success of that method in molecular physics is based on the small mass ratio, electron mass to nuclear mass. In the atomic application such a small parameter does not exist. Nevertheless the method works surprisingly well in the lower part of the spectrum. For increasing excitation energy the method becomes shaky. Near ionization threshold, it breaks even down. The author will present elsewhere an improved Born-Oppenheimer method. First pilot developments and comparison with the experimental situation are presented already here. Inclusion of a momentum-momentum radial coupling delivers an improved basis. We show that our extended Born-Oppenheimer approach leads to a deformation of the whole potential energy surface during the collision. In consequence of this deformation we outline a quantum derivation of the Wannier threshold cross section law, and we show that (e, 2e) angular distribution data are strongly influenced by that surface deformation. Finally, we present a mechanism for electron pair formation and decay leading to a supercurrent independent of the temperature. Our framework can be extended to more than two electrons, say 3 or 4. We conclude that our improved Born-Oppenheimer method <a href="#ref.1">[1]</a> is expected not only to deliver better numerical data, but it is expected to describe also the Wannier phenomenon. The idea of the new theory together with first qualitative results is presented in this paper.展开更多
The matrix elements of the correlation function between symmetric potential harmonics were first simplified into the analytical summation of the grand angular momentum. The correlation-function potential-harmonic and... The matrix elements of the correlation function between symmetric potential harmonics were first simplified into the analytical summation of the grand angular momentum. The correlation-function potential-harmonic and generalized Laguerre function method (CFPHGLF) proposed by us recently was then applied to directly solve the Schrodinger equation for n3S(n=2-5) excited states of the helium atom. With only 12 PHs, the convergent eigenenergies of 23S, 33S, 43S and 53S states were 2.17427, 2.06849, 2.03644, 2.02257 Eh, respectively. The errors only were 0.00096, 0.00020, 0.00007, 0.00005 Eh, when compared with the exact Hylleraas variational results respectively.展开更多
COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However...COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However, the problem of slow convergence in the hyperangle part still exists as other hyperspherical harmonics (HH) methods do. To solve the prob-展开更多
The potential-harmonic and generalized Laguerre function method (PHGLF) was modified into the correlation-function potential-harmonic and generalized Laguerre function method (CFPHGLF). The eigenenergies for 21S, 31S ...The potential-harmonic and generalized Laguerre function method (PHGLF) was modified into the correlation-function potential-harmonic and generalized Laguerre function method (CFPHGLF). The eigenenergies for 21S, 31S and 41S states of helium-like systems from the CFPHGLF are much more accurate than those from the previous PHGLF, but the eigenenergy for the 11S is not as good as that from the PHGLF method. The results indicate that the electron-nucleus cusp plays more important role than the electron-electron cusp and the cluster structure for the loosely bound excited states, and that the electron-electron cusp is absolutely essential for the tightly bound ground state.展开更多
The wave functions of the n1,3p (n=2, 3, 4) and the n 1,3D (n=3, 4, 5 ) low-lying states of the helium atom are expanded into the complete sets of the symmetrically adapted basis functions from hyperspherical harmonic...The wave functions of the n1,3p (n=2, 3, 4) and the n 1,3D (n=3, 4, 5 ) low-lying states of the helium atom are expanded into the complete sets of the symmetrically adapted basis functions from hyperspherical harmonic functions in the angle part and of generalized Laguerre functions in the radial part respectively, and are then augmented by the simplest type of Jastrow correlation factor to incorporate electron-nucleus cusp only. The excellent agreement between the present nonrelativistic eigen-energies and those from the sophisticated configuration interaction (CI) method for the examined states indicates that the hyperspherical harmonic method can also be applied to the P and the D excited states of the helium atom.展开更多
Recently Deng Conghao et al. proposed a new method for the direct solution of the many-body Schrdinger equation. Calculations based on this method for the ground-state energy of He indicated that the convergence of th...Recently Deng Conghao et al. proposed a new method for the direct solution of the many-body Schrdinger equation. Calculations based on this method for the ground-state energy of He indicated that the convergence of the hyperspherical harmonics (HH) expansion is slow and not satisfactory. A ground-state energy of-2.90328 a.u. was obtained in Ref.[2] with 361 HH and 4 GLF. In order to展开更多
A complete potential harmonic scheme is presented,including the linked coupled hyperradial ordi nary differential equations and the secular equation of eigencnergy It has been used to directly solve the Scchrodinger e...A complete potential harmonic scheme is presented,including the linked coupled hyperradial ordi nary differential equations and the secular equation of eigencnergy It has been used to directly solve the Scchrodinger equations of helium-like three-body systems (nuclear charge Z=1-9),and very accurate ground state eigonenergies as well as low-lying singlet excited state ones have been obtained展开更多
文摘Two-electron atoms have been investigated near threshold of double escape within the framework of hyperspherical coordinates. A particularly useful set of hyperspherical angles has been used. It is well known for many years that the hyperradial motion is nearly separable from the hyperspherical angular motion. Therefore, the Born-Oppenheimer separation method should be useful. However, the success of that method in molecular physics is based on the small mass ratio, electron mass to nuclear mass. In the atomic application such a small parameter does not exist. Nevertheless the method works surprisingly well in the lower part of the spectrum. For increasing excitation energy the method becomes shaky. Near ionization threshold, it breaks even down. The author will present elsewhere an improved Born-Oppenheimer method. First pilot developments and comparison with the experimental situation are presented already here. Inclusion of a momentum-momentum radial coupling delivers an improved basis. We show that our extended Born-Oppenheimer approach leads to a deformation of the whole potential energy surface during the collision. In consequence of this deformation we outline a quantum derivation of the Wannier threshold cross section law, and we show that (e, 2e) angular distribution data are strongly influenced by that surface deformation. Finally, we present a mechanism for electron pair formation and decay leading to a supercurrent independent of the temperature. Our framework can be extended to more than two electrons, say 3 or 4. We conclude that our improved Born-Oppenheimer method <a href="#ref.1">[1]</a> is expected not only to deliver better numerical data, but it is expected to describe also the Wannier phenomenon. The idea of the new theory together with first qualitative results is presented in this paper.
基金Project supported by the National Natural Science Foundation of China and by the Natural Science Foundation for Youth of Shandong University.
文摘 The matrix elements of the correlation function between symmetric potential harmonics were first simplified into the analytical summation of the grand angular momentum. The correlation-function potential-harmonic and generalized Laguerre function method (CFPHGLF) proposed by us recently was then applied to directly solve the Schrodinger equation for n3S(n=2-5) excited states of the helium atom. With only 12 PHs, the convergent eigenenergies of 23S, 33S, 43S and 53S states were 2.17427, 2.06849, 2.03644, 2.02257 Eh, respectively. The errors only were 0.00096, 0.00020, 0.00007, 0.00005 Eh, when compared with the exact Hylleraas variational results respectively.
文摘COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However, the problem of slow convergence in the hyperangle part still exists as other hyperspherical harmonics (HH) methods do. To solve the prob-
基金Project supported by the National Natural Science Foundation of China
文摘The potential-harmonic and generalized Laguerre function method (PHGLF) was modified into the correlation-function potential-harmonic and generalized Laguerre function method (CFPHGLF). The eigenenergies for 21S, 31S and 41S states of helium-like systems from the CFPHGLF are much more accurate than those from the previous PHGLF, but the eigenenergy for the 11S is not as good as that from the PHGLF method. The results indicate that the electron-nucleus cusp plays more important role than the electron-electron cusp and the cluster structure for the loosely bound excited states, and that the electron-electron cusp is absolutely essential for the tightly bound ground state.
基金Supported by the National Natural Science Foundation of China(No. 29703003).
文摘The wave functions of the n1,3p (n=2, 3, 4) and the n 1,3D (n=3, 4, 5 ) low-lying states of the helium atom are expanded into the complete sets of the symmetrically adapted basis functions from hyperspherical harmonic functions in the angle part and of generalized Laguerre functions in the radial part respectively, and are then augmented by the simplest type of Jastrow correlation factor to incorporate electron-nucleus cusp only. The excellent agreement between the present nonrelativistic eigen-energies and those from the sophisticated configuration interaction (CI) method for the examined states indicates that the hyperspherical harmonic method can also be applied to the P and the D excited states of the helium atom.
文摘Recently Deng Conghao et al. proposed a new method for the direct solution of the many-body Schrdinger equation. Calculations based on this method for the ground-state energy of He indicated that the convergence of the hyperspherical harmonics (HH) expansion is slow and not satisfactory. A ground-state energy of-2.90328 a.u. was obtained in Ref.[2] with 361 HH and 4 GLF. In order to
基金Project supported hy the National Natural Science Foundation of Chinathe Science Foundation for Youth of Shandong University
文摘A complete potential harmonic scheme is presented,including the linked coupled hyperradial ordi nary differential equations and the secular equation of eigencnergy It has been used to directly solve the Scchrodinger equations of helium-like three-body systems (nuclear charge Z=1-9),and very accurate ground state eigonenergies as well as low-lying singlet excited state ones have been obtained
