中高能电子被氟代甲烷散射的总截面计算

利用可加性规则,使用Hartree-Fock 波函数,采用被束缚原子概念修正过的复光学势,首次在100～5 000eV内对电子被具有较多电子数的氟代甲烷分子散射的总截面进行了计算,且将计算值与实验值及经验公式进行了比较,得出了被束缚原子概念修正过的复光学势可成功用于"电子-氟代甲烷"散射总截面计算的结论;研究了"电子-氟代甲烷"的散射总截面与目标分子总电子数及电子入射能量间的关系,初步分析了结构因子与总电荷数相关的原因,并指出了对复光学势进行进一步修正时应遵循的原则.     

100～5 000 eV下电子被等电子(Z=10)分子CH4、H2O、HF及NH3散射的总截面计算

利用可加性规则,使用Roothaan-Hartree-Fock波函数,在100～5 000 eV下首次采用由束缚原子概念修正过的复光学势,对电子被等电子(Z=10)分子CH4、H2O、HF和NH3散射的总截面进行了计算.束缚原子不同于自由原子之处,是束缚原子考虑了在不同分子中电子云的不同重叠,将计算结果与实验及其它计算结果进行了比较.结果表明,利用被束缚原子概念修正过的复光学势及可加性规则进行计算,其结果的精度要比利用未被束缚原子概念修正过的复光学势及可加性规则进行计算得到的结果好.     

Total cross sections for scattering of electrons from O2, H2O, H2, O3, CO and CO2 at 100－2000eV

A complex optical model potential rewritten by the concept of bonded atom, which considers the overlap of electron clouds, is employed to calculate the total cross sections for electron scattering from several simple molecules (O_2, H_2O, H_2, O_3, CO and CO_2) consisting of C, H and O atoms in an incident energy range of 100－2000eV by the use of the additivity rule at Hartree－Fock level. In the study, the complex optical potential composed of static, exchange, correlation polarization plus absorption contributions firstly uses the bonded-atom concept. The quantitative molecular total cross section results are compared with experimental data and with the other calculations wherever available and good agreement is obtained. It is shown that the additivity rule along with the complex optical model potential rewritten by the concept of bonded atom can be used successfully to calculate the total cross section of electron－molecule scattering above 100eV, whereas the rule together with the complex optical model potential not rewritten by the concept of bonded atom is only successfully used above 300－500eV. So, the introduction of the bonded-atom concept in the complex optical potential can improve the accuracy of the total cross section calculations.     

一种考虑几何屏蔽效应的计算“电子-分子”散射总截面的可加性规则修正方法

在考虑分子内原子间的几何屏蔽效应随电子入射能量变化的基础上, 提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的可加性规则修正方法. 利用这一修正后的可加性规则并使用“电子-C, H, O, N原子”散射总截面的实验数据, 在50—5000 eV内计算了电子被NO, N₂O, NO₂和C₂H₆分子散射的总截面, 且将计算结果与实验结果及其他理论结果进行了比较. 结果表明, 利用这一方法修正过的可加性规则进行计 关键词： 电子散射 可加性规则 总截面 几何屏蔽效应     

30-3000eV的正电子被O2、H2O及CH4散射的总截面计算

使用可加性规则，在Hartree-Fock水平上计算了30-3000eV的正电子被三个分子（O2、H2O及CH4）散射的总截面。计算正电子被三个分子散射的总截面时，首次使用了被束缚原子概念修正过的复光学势（这一复光学势考虑了分子中两个原子间的电子云重叠效应）。将正电子被这三个分子散射的总截面计算结果与实验结果及其它理论计算结果进行了比较，结果显示出在30-3000eV内，文中的计算结果与实验结果及其它理论计算结果具有较好的一致性。因此，可加性规则与修正后的复光学势相结合，完全适用于正电子被分子散射的总截面的计算。     

30-5000eV的电子被若干分子散射的总截面计算的一种修正势方法

利用可加性规则，使用Hartree-Fock波函数，采用由束缚原子概念修正过的复光学势，在30~5000eV这一较大的能域内对电子被N2、NO、NO2、CH4、CF4、CF3H、C2H2及C2H4散射的总截面进行了计算。束缚原子不同于自由原子之处，是束缚原子概念考虑了不同分子中的不同的电子云重叠情况，并根据电子云的重叠情况对复光学势进行修正。文中，将定量的计算结果与实验结果及其它理论计算结果进行了比较，结果显示出在30~5000eV内，计算结果与实验结果及其它理论计算结果间有较好的一致性。同时结果也表明，在较低的能量下，尤其是当入射电子的能量低于500eV时，利用被束缚原子概念修正过的复光学势进行计算得到的结果，要比利用未被束缚原子概念修正的复光学势计算得到的结果更接近于实验值。因此，在复光学势中考虑电子云的重叠效应可改善电子被分子散射的总截面的计算精度。     

A modification potential method of calculating total cross sections of electrons scattering from complex molecules C2H6, C2F6, C6H6 and C6F6 at 100 eV-5000 eV

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C总交叉断面 电子散射 添加规则 原子分子碰撞 电子云total cross section, electrons scattering, additivity rule, atomic and molecular collisionProject supported by the National Natural Science Foundation of China (Grant No 10574039).2005-11-102005-11-102005-11-30A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 using the aclditivity rule model at Hartree-Fock level over the energy range from 100 eV to 5000 eV. The total cross sections are quantitatively compared with those obtained by experiments wherever available, and they are in good agreement with each other over a wide energy range. It is shown that the modified potential together with the additivity rule model is completely suitable for the calculation of total cross sections of electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 above 200 eV-300 eV.     

正电子被分子散射总截面的计算

将光学势方法与可加性规则（ａｄｄｉｔｉｖｉｔｙｒｕｌｅ）相结合，我们计算了能量在１０－１０００ｅＶ范围内正电子被分子（Ｈ２，Ｎ２，ＨＣｌ，ＮＨ３，ＣＨ４，ＳＦ６）散射的总截面，计算结果与已有的实验结果进行了比较。     

Electron-driven processes for furan,tetrahydrofuran and 2, 5-dimethylfuran

We present the study of electron-induced processes for biomolecules, furan (C₄H₄O) and tetrahydrofuran (C₄H₈O) as well as an industrial relevant molecule 2, 5-dimethylfuran (C₆H₈O) through various total cross sections for impact energies from threshold to 5 keV. We have employed spherical complex optical potential to calculate total cross sections Q_T and total elastic cross sections Q_el. Since these molecules are complex molecules, we have used the group additivity rule which incorporates molecular properties as well as geometry of the target to evaluate these cross sections. Dependence of Q_T and Q_el on number of electrons and correlation of dipole polarisability (α) and ionisation potential (I) with peak of total ionisation cross sections Q_ion is studied and important inferences are noted. The present results for these applied molecules are compared with previous data wherever available. This is the maiden attempt to report Q_el and Q_T for 2, 5-dimethylfuran.     

一种计算中、高能电子被分子散射总截面的修正势方法

在考虑分子内成键原子间的电子云重叠效应的基础上，提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的修正势方法.利用可加性规则及Hartree-Fock波函数，使用这一修正过的复光学势，在30—5000eV内对电子被4个等电子(Z=18)分子(HCl，H₂S，PH₃和SiH₄)散射的总截面进行了计算，并将理论计算值与实验结果及其他理论值进行了比较.结果表明，利用这一修正过的复光学势及可加性规则进行计算，所得理论值与实验结果更为接近. 关键词： 电子散射 总截面 可加性规则 束缚原子     

Positron scattering from alkaline-earth elements

The total (elastic + inelastic) cross sections fore ⁺ impact on alkaline-earth elements from Be to Ra are calculated by employing a complex spherical optical potential. This potential has static, polarization and absorption components. The positron energy range is from a few eV to several thousand eV. We have compared our elastic cross sections for Mg and Ca with the other available results and the agreement is good for energies above 100eV. We have also compared our absorption cross sections withe ⁻ ionization cross sections at high energies where our absorption cross sections are in good accord. We have made Bethe plots fore ⁺ scattering on these elements.     

Complex scattering potential – ionization contribution (CSP-ic) method for calculating total ionization cross sections on electron impact

In this article, we report calculations of total ionization cross sections, Q _ion , for simple atoms (C, N, O, F) and molecules (NO and NH₃)_{3}) of atmospheric interest on electron impact at energies from threshold to 2000 eV. We have employed the complex scattering potential – ionization contribution (CSP-ic) method for the present study. Attempt has been made to improve the method by computing the parameter that involves the ratio of sum of the total excitation cross sections (Σ Q _exc ) and total inelastic cross section (Q _inel ) at the peak of the inelastic cross section. The present study not only provided a better estimation of the parameter involved in the CSP-ic method but also provided better agreement with the available experimental and theoretical data on the ionization cross sections of the simple atomic and molecular targets studied here.     

Total cross sections for electrons scattering from simple molecules containing the larger atom sulfur at 30-5000eV

A complex optical model potential modified by the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds, is employed to calculate the total cross sections for electrons scattering from simple molecules （SO2, H2S, OCS, CS2 and SO3） containing the larger atom, sulfur, at 30-5000eV by using the additivity rule model at Hartree-Fock level. The quantitative molecular total cross section results are compared with those obtained in experiments and other calculations wherever available, and good agreement is obtained. It is shown that the additivity rule model together with the complex optical model potential modified by the concept of bonded atom can give the results closer to the experiments than the one unmodified by it. So, the introduction of bonded-atom concept in complex optical model potential betters the accuracy of the total cross section calculations of electrons from the molecules containing the larger atom, sulfur.     

Coupled-channel optical calculation for positron—lithium scattering

Positron scattering with atomic lithium is investigated by using a coupled-channel optical method.The ionization continuum and positronium formation channels are taken into account via a complex equivalent-local optical potential.The positronium formation cross sections and the ionization cross sections,as well as the total scattering cross sections,are reported at energies above 3 eV and compared with available experimental and theoretical data.     

Electron impact ionisation cross sections for atomic and molecular allotropes of phosphorous and arsenic

We report electron impact total ionisation cross sections for phosphorous (P), arsenic (As), diphosphorous (P₂), diarsenic (As₂), tetra phosphorous (P₄) and tetra arsenic (As₄) from the threshold of the target to 2000 eV. We employed spherical complex optical potential to compute total inelastic cross sections (Q_inel). The total ionisation cross section is extracted from the total inelastic cross section using the complex scattering potential–ionisation contribution method. The results of most of the targets studied here compare well with the measurements and the theoretical data wherever available. The correlation between the peak of ionisation cross sections with the number of target electrons and polarisability is also reported. It is observed that the maximum ionisation cross sections depend linearly on the number of target electrons and polarisability of the target. This linear correlation is used to predict the maximum ionisation cross sections for the targets (I₂, HI and PF₃) where no experimental data are available.     

中、高能电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面

在考虑分子内成键原子间的电子云重叠效应的基础上, 提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法. 利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势, 在100—1000eV内对电子被SO₂分子散射的微分截面、动量转移截面及弹性积分截面进行了计算, 并将计算结果与实验及其他理论结果进行比较. 结果表明, 利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准 关键词： 可加性规则 微分截面 动量转移截面 电子散射     

中高能正电子被CO，HCl，NH3及SiH4散射的总截面

利用可加性规则，使用Hartree-Fock波函数，采用由束缚原子概念修正过的复光学势(由静电势、极化势及吸收势三部分组成)，在30—3000eV内对正电子被CO，HCl，NH₃和SiH₄散射的总截面进行了计算，且将计算结果与实验结果及其他理论计算结果进行了比较.结果表明，利用被束缚原子概念修正过的复光学势及可加性规则进行计算，所得结果与实验结果的符合程度要比利用未被束缚原子概念修正的复光学势及可加性规则进行计算得到的结果好很多.因此，在复光学势中采用束缚原子概念可提高正电子被分子散射的总截面的计算准确度. 关键词： 正电子散射 可加性规则 束缚原子 总截面     

Differential, elastic integral and moment transfer cross sections for electron scattering from N2 at intermediate- and high-energies

A complex optical model potential modified by incorporating the concept of bonded atom, with the overlapping effect of electron clouds between two atoms in a molecule taken into consideration, is firstly employed to calculate the differential cross sections, elastic integral cross sections, and moment transfer cross sections for electron scattering from molecular nitrogen over the energy range 300—1000eV by using additivity rule model at Hartree—Fock level. The bonded-atom concept is used in the study of the complex optical model potential composed of static, exchange, correlation polarization and absorption contributions. The calculated quantitative molecular differential cross sections, elastic integral cross sections, and moment transfer cross sections are compared with the experimental and theoretical ones wherever available, and they are found to be in good agreement with each other. It is shown that the additivity rule model together with the complex optical model potential modified by incorporating the concept of bonded atom is completely suitable for the calculations of differential cross section, elastic integral cross section and moment transfer cross section over the intermediate- and high-energy ranges.     

A Correlation Potential Method for Electron Scattering Total Cross Section Calculations on Several Diatomic and Polyatomic Molecules over Energy Range 10 ～ 5000 eV

A complex optical model potential correlated by the concept of bonded atom, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the total cross sections for electron scattering on several molecules (NH₃, H₂O, CH₄, CO, N₂, O₂, and C₂H₄) over the energy range 10～5000 eV using the additivity rule model at Hartree-Fock level. The difference between the bonded atom and the free one in states is that the overlapping effect of electron clouds of bonded atoms in a molecule is considered. The quantitative total cross sections are compared with the experimental data and with the other calculations wherever available and good agreement is obtained over the energy range 10～5000 eV. It is shown that the correlated calculations are much closer to the available experimental data than the uncorrelated ones at lower energies, especially below 500 eV. Therefore, considering the overlapping effect of electron clouds in the complex optical model potential could be helpful for the better accuracy of the total cross section calculations of electron scattering from molecules.     

中高能电子被甲烷及氯代甲烷散射的总截面

利用可加性规则，使用HartreeFock波函数，采用由束缚原子概念修正过的复光学势（由静 电势、交换势、修正极化势及吸收势这四部分组成），在较大的能量(30—5000eV)范围内对 电子被甲烷及氯代甲烷（CH₄，CCl₄，CHCl₃，CH₂Cl₂和CH ₃Cl）散射的总截面进行了计算，且将计算结果与实验结果及其他理论计算 结果进行 了比较.结果表明，利用被束缚原子概念修正过的复光学势及可加性规则进行计算，所得结 果的精度要比利用未被束缚原子概念修正的复光学势及可加性规则进行计算得到的结果好很 多.因此，在复光学势中采用束缚原子概念可提高电子被分子散射的总截面的计算准确度. 关键词： 电子散射 可加性规则 束缚原子 总截面