The 1^10^+ 1^1(-1)^+and 1^1(2)^+ states of the helium atom in the magnetic field regime between 0 and 100 a.u. are studied using a full configuration-interaction (CI) approach. The total energies, derivatives...The 1^10^+ 1^1(-1)^+and 1^1(2)^+ states of the helium atom in the magnetic field regime between 0 and 100 a.u. are studied using a full configuration-interaction (CI) approach. The total energies, derivatives of the total energy with respect to the magnetic field and ionisation energies are calculated with Hylleraas-like functions in spherical coordinates in low to intermediate fields and Hylleraas Caussian functions in cylindrical coordinates in intermediate to high fields, respectively. In intermediate fields, the total energies and ionisation energies are determined in terms of Hermite interpolation, based on the results obtained with the two above-mentioned basis functions. Calculations show that the current method can produce lower total energies and larger ionisation energies, and make the two ionisation energy curves obtained with the two above-mentioned basis functions join smoothly in intermediate fields. Comparisons are also made with previous works.展开更多
We proposed a simple potential harmonic(PH) scheme for calculating the non\|relativistic radial correlation energies of atomic systems. The scheme was applied to the low\|lying \%n\%\+1\%S\%(\%n\%=1,2) and \%n\%\+3\%...We proposed a simple potential harmonic(PH) scheme for calculating the non\|relativistic radial correlation energies of atomic systems. The scheme was applied to the low\|lying \%n\%\+1\%S\%(\%n\%=1,2) and \%n\%\+3\%S\%(\%n\%=2,3) states of the helium atom. The results exhibit a very stable convergence characterization in both the angular and radial directions with PH and generalized Laguerre functions(GLF) respectively, even though the method is non\|variational one. The ninth significant figure of the non\|relativistic radial energy(NRE) calculated for the ground state exactly agrees with that of the most accurate literature data from the modified configuration interaction method. The convergent NRE′s for the excited states 2\+1\%S\%, 2\+3\%S\% and 3\+3\%S\% with the similar accuracy were also obtained.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
We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with imp...We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with implement of finite element discrete variable representation.The studies of joint energy distributions and joint angular distributions of the two photoelectrons reveal the competition for ionized probabilities between the photoelectrons with odd parity and photoelectrons with even parity in single-XUV-photon double ionization process in the presence of weak infrared laser field,and such a competition can be modulated by changing the intensity of the weak assisting-IR laser pulses.The emission angles of the two photoelectrons can be adjusted by changing the laser parameters as well.We depict how the assisting-IR laser field enhances and/or enables the back-to-back and side-by-side emission of photoelectrons created in double ionization process.展开更多
The g-factors of the 2 3P, 2 1P, and 3 3P states of the helium atom are calculated by using the vatiational wave functions constructed from the linear combinations of Slater-type basis sets. The relativistic correctio...The g-factors of the 2 3P, 2 1P, and 3 3P states of the helium atom are calculated by using the vatiational wave functions constructed from the linear combinations of Slater-type basis sets. The relativistic corrections to order α 2(a.u.) and the effect of the motion of the center of mass are treated by using first-order perturbation theory. Most of our predicted results are in good agreement with recent results of Yan and Drake, which were obtained by using the wave functions with doubled Hylleraas coordinates. Based on the analysis of the convergence pattern in our calculation, we believe that our predicted value of the δg L-factor for 3 3P state in 4He, 2.914 15×10 -7 , ought to be reasonable and accurate, although there are no corresponding experimental data available in the liteature yet to be compared with.展开更多
The diffusion behaviors of helium atoms at two symmetric grain boundaries (Σ5<001>{210} andΣ3<110> {112}) of Pd were investigated using molecular dynamics simulations through an analytical embedded-atom ...The diffusion behaviors of helium atoms at two symmetric grain boundaries (Σ5<001>{210} andΣ3<110> {112}) of Pd were investigated using molecular dynamics simulations through an analytical embedded-atom method(MAEAM) model. The simulations demonstrate that the interstitial helium atoms are easily trapped at the grain boundaries and precipitated into clusters. Due to the closed-shell electronic configurations of both helium and palladium, Pd grain boundaries yield strong capability of retaining helium atoms. By calculating the mean square displacements(MSD) of an interstitial helium atom at the grain boundaries, the diffusion coefficients were determined, and the linear fits to Arrhenius relation. The diffusion activation energies of interstitial helium atom at these two Pd grain boundaries were also evaluated.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
A fast-rising gas temperature is due to frequent collisions of the heavy particles in an atmosphericpressure dielectric barrier discharge.In this paper,a two-dimensional fluid model is applied to investigate the influ...A fast-rising gas temperature is due to frequent collisions of the heavy particles in an atmosphericpressure dielectric barrier discharge.In this paper,a two-dimensional fluid model is applied to investigate the influences of rising gas temperature on an atmospheric-pressure helium dielectric barrier discharge.With the increase in the gas temperature,it is found that:(1)a helium discharge can evolve from the discharge column to a homogeneous discharge;(2)the breakdown time is in advance and the gas breakdown voltage decreases;(3)the spatial distribution evolution of the electron density is similar to that of the helium atom density.The most significant discrepancy between them is that the electron densities are high at some positions where the helium atom densities are nevertheless low.Furthermore,the radial reduced electric fields are obtained under different gas temperatures.The physical reasons for the gas temperature effects are discussed.The simulation results provide a better understanding of the roles of the radial reduced electric field and the heavy particle.展开更多
In this paper, author investigated the effect of the Coulomb potential of the core of atomic helium on the rescattering processes. Through the calculation author concluded that the Coulomb potential effect may not pla...In this paper, author investigated the effect of the Coulomb potential of the core of atomic helium on the rescattering processes. Through the calculation author concluded that the Coulomb potential effect may not play an important role in causing the discrepancy between the experimental data and theoretical results of Kuchievs model, and the NS ionization is dependent on the frequency of the laser field. Furthermore, it is concluded that the strength of the laser field and the charge number of the core affect the frequency regime corresponding to the peak value of the NS ionization rate.展开更多
Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy ...Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy eigenvalues of bound 1sns(~1S^e)(n=1-6)states and the resonance parameters i.e.positions and widths of^lS^e states due to 2sns(n=2-5)and 2pnp(n=2-5)configurations of confined helium below N=2 ionization threshold of He^+have been estimated.The two-parameter(Depth and Width)finite oscillator potential is used to represent the confining potential due to the quantum dot.It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size.It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters.A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here.展开更多
Solid helium bubbles were directly observed in the helium ion implanted tungsten(W), by different transmission electron microscopy(TEM) techniques at room temperature. The diameters of these solid helium bubbles r...Solid helium bubbles were directly observed in the helium ion implanted tungsten(W), by different transmission electron microscopy(TEM) techniques at room temperature. The diameters of these solid helium bubbles range from1 nm to 8 nm in diameter with the mean bubble size about 3 nm. The selected area electron diffraction(SAED) and fast Fourier transform(FFT) images revealed that solid helium bubbles possess body-centered cubic(bcc) structure with a lattice constant of 0.447 nm. High-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)images further confirmed the existence of helium bubble in tungsten. The present findings provide an atomic level view of the microstructure evolution of helium in the materials, and revealed the existence of solid helium bubbles in materials.展开更多
The embedded-atom method(EAM)is used to study the behavior of helium in meta-ls.By fitting the measured parameters such as the activation energy and the heat of solution,the EAM potentials of helium in nickel are extr...The embedded-atom method(EAM)is used to study the behavior of helium in meta-ls.By fitting the measured parameters such as the activation energy and the heat of solution,the EAM potentials of helium in nickel are extracted.Based upon the EAM potentials,thebinding energy and the self-trapping of helium in nickel are investigated with molecular dynam-ics simulation.展开更多
There is much different type of selective detectors for GC but emission spectroscopic detectors are few.We developed the radio frequency helium glow discharge plasma detector for capillary GC.It attached polychrometor...There is much different type of selective detectors for GC but emission spectroscopic detectors are few.We developed the radio frequency helium glow discharge plasma detector for capillary GC.It attached polychrometor to detect full spectrum simultaneously and achieved sensitive,selective detection ability for various compounds as a novel element selective detector.The application of this system will be reported.展开更多
In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</e...In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</em>, and 4<em>snp</em> Helium-like systems. Then we also applied the variational procedure of the Modified Atomic Orbital Theory to the computations of total energies, excitation energies of doubly-excited states 2<em>snp</em>, 3<em>snp</em>, 4<em>snp</em> types of Helium-like systems. The results obtained in this work are in good agreement with the experimental and theoretical values available.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10874133)
文摘The 1^10^+ 1^1(-1)^+and 1^1(2)^+ states of the helium atom in the magnetic field regime between 0 and 100 a.u. are studied using a full configuration-interaction (CI) approach. The total energies, derivatives of the total energy with respect to the magnetic field and ionisation energies are calculated with Hylleraas-like functions in spherical coordinates in low to intermediate fields and Hylleraas Caussian functions in cylindrical coordinates in intermediate to high fields, respectively. In intermediate fields, the total energies and ionisation energies are determined in terms of Hermite interpolation, based on the results obtained with the two above-mentioned basis functions. Calculations show that the current method can produce lower total energies and larger ionisation energies, and make the two ionisation energy curves obtained with the two above-mentioned basis functions join smoothly in intermediate fields. Comparisons are also made with previous works.
基金Supported by the National Natural Science Foundation of China(No. 2 970 30 0 3)
文摘We proposed a simple potential harmonic(PH) scheme for calculating the non\|relativistic radial correlation energies of atomic systems. The scheme was applied to the low\|lying \%n\%\+1\%S\%(\%n\%=1,2) and \%n\%\+3\%S\%(\%n\%=2,3) states of the helium atom. The results exhibit a very stable convergence characterization in both the angular and radial directions with PH and generalized Laguerre functions(GLF) respectively, even though the method is non\|variational one. The ninth significant figure of the non\|relativistic radial energy(NRE) calculated for the ground state exactly agrees with that of the most accurate literature data from the modified configuration interaction method. The convergent NRE′s for the excited states 2\+1\%S\%, 2\+3\%S\% and 3\+3\%S\% with the similar accuracy were also obtained.
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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774131 and 91850114).
文摘We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with implement of finite element discrete variable representation.The studies of joint energy distributions and joint angular distributions of the two photoelectrons reveal the competition for ionized probabilities between the photoelectrons with odd parity and photoelectrons with even parity in single-XUV-photon double ionization process in the presence of weak infrared laser field,and such a competition can be modulated by changing the intensity of the weak assisting-IR laser pulses.The emission angles of the two photoelectrons can be adjusted by changing the laser parameters as well.We depict how the assisting-IR laser field enhances and/or enables the back-to-back and side-by-side emission of photoelectrons created in double ionization process.
文摘The g-factors of the 2 3P, 2 1P, and 3 3P states of the helium atom are calculated by using the vatiational wave functions constructed from the linear combinations of Slater-type basis sets. The relativistic corrections to order α 2(a.u.) and the effect of the motion of the center of mass are treated by using first-order perturbation theory. Most of our predicted results are in good agreement with recent results of Yan and Drake, which were obtained by using the wave functions with doubled Hylleraas coordinates. Based on the analysis of the convergence pattern in our calculation, we believe that our predicted value of the δg L-factor for 3 3P state in 4He, 2.914 15×10 -7 , ought to be reasonable and accurate, although there are no corresponding experimental data available in the liteature yet to be compared with.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475021 and the Natural Science Foundation of Guangdong Province under Grant No. 04009519
基金The project supported by National Natural Science Foundation of China under Grant No. 10147207, the Natural Science Foundation of Chongqing Science and Technology Committee under Grant No. 2005BB8267, and the Fundamental Research Foundation of Chongqing Education Committee under Grant No. KJ060813
基金Project(50371026) supported by the National Natural Science Foundation of China Project supported by the Natural Science Foundation of Hunan Province Project(20040546) supported by the Science, Technology Foundation of China Academy of Engineering Physics
文摘The diffusion behaviors of helium atoms at two symmetric grain boundaries (Σ5<001>{210} andΣ3<110> {112}) of Pd were investigated using molecular dynamics simulations through an analytical embedded-atom method(MAEAM) model. The simulations demonstrate that the interstitial helium atoms are easily trapped at the grain boundaries and precipitated into clusters. Due to the closed-shell electronic configurations of both helium and palladium, Pd grain boundaries yield strong capability of retaining helium atoms. By calculating the mean square displacements(MSD) of an interstitial helium atom at the grain boundaries, the diffusion coefficients were determined, and the linear fits to Arrhenius relation. The diffusion activation energies of interstitial helium atom at these two Pd grain boundaries were also evaluated.
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.
基金supported by the Liaoning Provincial Department of Education Fund(No.LJ2020008)。
文摘A fast-rising gas temperature is due to frequent collisions of the heavy particles in an atmosphericpressure dielectric barrier discharge.In this paper,a two-dimensional fluid model is applied to investigate the influences of rising gas temperature on an atmospheric-pressure helium dielectric barrier discharge.With the increase in the gas temperature,it is found that:(1)a helium discharge can evolve from the discharge column to a homogeneous discharge;(2)the breakdown time is in advance and the gas breakdown voltage decreases;(3)the spatial distribution evolution of the electron density is similar to that of the helium atom density.The most significant discrepancy between them is that the electron densities are high at some positions where the helium atom densities are nevertheless low.Furthermore,the radial reduced electric fields are obtained under different gas temperatures.The physical reasons for the gas temperature effects are discussed.The simulation results provide a better understanding of the roles of the radial reduced electric field and the heavy particle.
文摘In this paper, author investigated the effect of the Coulomb potential of the core of atomic helium on the rescattering processes. Through the calculation author concluded that the Coulomb potential effect may not play an important role in causing the discrepancy between the experimental data and theoretical results of Kuchievs model, and the NS ionization is dependent on the frequency of the laser field. Furthermore, it is concluded that the strength of the laser field and the charge number of the core affect the frequency regime corresponding to the peak value of the NS ionization rate.
基金Financial Support under Grant No.37(3)/14/27/2014-BRNS from the Department of Atomic Energy,BRNS,Government of IndiaFinancial Support under Grant No.PSW-160/14-15(ERO)from University Grants Commission,Government of India
文摘Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy eigenvalues of bound 1sns(~1S^e)(n=1-6)states and the resonance parameters i.e.positions and widths of^lS^e states due to 2sns(n=2-5)and 2pnp(n=2-5)configurations of confined helium below N=2 ionization threshold of He^+have been estimated.The two-parameter(Depth and Width)finite oscillator potential is used to represent the confining potential due to the quantum dot.It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size.It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters.A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here.
基金Project supported by the ITER-National Magnetic Confinement Fusion Program(Grant Nos.2010GB109000,2011GB108009,and 2014GB123000)the National Natural Science Foundation of China(Grant No.11075119)
文摘Solid helium bubbles were directly observed in the helium ion implanted tungsten(W), by different transmission electron microscopy(TEM) techniques at room temperature. The diameters of these solid helium bubbles range from1 nm to 8 nm in diameter with the mean bubble size about 3 nm. The selected area electron diffraction(SAED) and fast Fourier transform(FFT) images revealed that solid helium bubbles possess body-centered cubic(bcc) structure with a lattice constant of 0.447 nm. High-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)images further confirmed the existence of helium bubble in tungsten. The present findings provide an atomic level view of the microstructure evolution of helium in the materials, and revealed the existence of solid helium bubbles in materials.
基金Supported by the National Hi-Tech ICF Committee of China under Grant No 2004AA84ts08, the National Natural Science Foundation of China under Grant No 10574019, the Chemical Sciences, Geosciences, and Biosciences Division, 0ffice of Basic Energy Sciences, 0ffice of Science, Department of Energy of USA, and the National Science Foundation of USA.
基金The project supported by the National Natural Science Foundation of China
文摘The embedded-atom method(EAM)is used to study the behavior of helium in meta-ls.By fitting the measured parameters such as the activation energy and the heat of solution,the EAM potentials of helium in nickel are extracted.Based upon the EAM potentials,thebinding energy and the self-trapping of helium in nickel are investigated with molecular dynam-ics simulation.
文摘There is much different type of selective detectors for GC but emission spectroscopic detectors are few.We developed the radio frequency helium glow discharge plasma detector for capillary GC.It attached polychrometor to detect full spectrum simultaneously and achieved sensitive,selective detection ability for various compounds as a novel element selective detector.The application of this system will be reported.
文摘In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</em>, and 4<em>snp</em> Helium-like systems. Then we also applied the variational procedure of the Modified Atomic Orbital Theory to the computations of total energies, excitation energies of doubly-excited states 2<em>snp</em>, 3<em>snp</em>, 4<em>snp</em> types of Helium-like systems. The results obtained in this work are in good agreement with the experimental and theoretical values available.