BeCl_2分子的低能电子弹性散射研究

基于R矩阵理论方法,通过构建BeCl_2分子的静态交换势模型(SE),静态交换加极化势模型(SEP)和密耦合模型(CC),在0-10 eV能量范围内首次研究了低能电子与BeCl_2分子的散射动力学过程,预测了弹性散射积分截面,并在三种模型中分别发现一个来自B_(2u)和B_(3u)对称性贡献的势形共振态.讨论了这些共振态随着极化效应的变化,获得了收敛的截面和共振态结果.进一步使用POLYDCS程序首次计算了电子与BeCl_2分子的散射微分截面(DCS)以及动量转移截面(MTCS).当前研究结果将为天体物理和等离子体物理提供重要的截面数据.     

甲硫醇的低能电子弹性碰撞截面

使用R-matrix方法在静态交换和静态交换加极化两种模型下研究电子-甲硫醇的弹性散射．计算的弹性散射截面与已有的实验结果符合的很好．静态交换极化模型探测到了两个具有2A'对称性的形 状共振态,能量位置分别在4.06和8.32 eV．通过波恩修正,用更高的分波l>4获得了收敛的截面．还使用计算的动量转移截面数据计算了200～30000 K的高效电子碰撞频率.     

惰性气体原子对2500eV电子的绝对弹性散射微分截面

在入射电子能量为2500eV，散射角为4°—15°的条件下测量了氦、氖、氩的相对弹性散射微分截面，并采用非弹性散射的广义振子强度为标准进行刻度，得到了2500eV能量下的绝对弹性散射微分截面值.所得结果与前人的理论和实验结果作了比较. 关键词：     

快中子在Li核上的弹性散射微分截面

用伴随粒子飞行时间法测量了14.7MeV中子在⁶Li和⁷Li核上的弹性散射截面,并用蒙特卡罗方法对中子在样品中的通量衰减、多次散射作了修正.本文工作与他人工作以及理论数据作了比较.给出了截面的勒让德系数;截面实验点总误差在10%到15%之间,其中统计误差为1%-5%.     

14.2MeV中子在锆上弹性散射的微分截面

用伴随粒子飞行时间方法,在10°—140°范围内测量了14.2MeV中子在Zr上的弹性散射微分截面.用蒙特卡洛方法对中子在样品中的通量衰减,多次散射及有限角分辨进行了修正;并将测量数据与光学模型理论计算及他人的结果作了比较.     

计算中低能量电子与水分子弹性散射微分截面

运用耦合通道光学势方法计算了在中低能量下的电子与水分子碰撞弹性散射微分截面,其中靶的极化效应被包含在一个从头算的等价局域势中.随后将计算结果与实验值和其它理论计算结果进行了比较.结果显示这种计算方法对于电子与极化分子体系碰撞是非常适用的.     

慢电子被氧原子弹性散射的截面计算

采用Ｈａｒａ ｆｒｅｅ－ｅｌｅｃｔｒｏｎ－ｇａｓ ｅｘｃｈａｎｇｅ ａｐｐｒｏｘｉｍａｔｉｏｎ（ＨＦＥＧＥ）交换势和本文作者提出的极化势，用等效势模型计算了能量在０．１３６－１２ｅＶ内的ｅ－Ｏ弹性散射总截面和动量转移截面，结果与Ｔｈｏｍａｓ和Ｎｅｓｂｅｔ的理论计算结果以及实验结果作了比较。     

低能电子在水中的弹性散射

基于平均散射截面概念,结合Mott截面,计算E≤10 keV范围低能电子在水中弹性散射的微分散射截面、总散射截面及弹性散射角概率分布,与应用Rutherford模型的计算结果及实验结果符合较好.在此基础上,给出一个低能电子在水中弹性散射的模拟方法,既严格可靠,又能够方便地应用于低能电子在水中径迹结构的模拟.     

Elastic electron scattering with CH2Br2 and CCl2Br2: The role of the polarization effects

We present elastic electron scattering cross sections with holmethane molecules CH₂Br₂ and CCl₂Br₂ in the low-energy region ranging from 0.01 eV to 20 eV. The calculations are performed with the R-matrix method in static-exchange plus polarization (SEP) and close-coupling (CC) approximations. The integral, differential, and momentum transfer cross sections are calculated. The convergence of the obtained cross sections is checked at four different levels of SEP approximation. The predicted positions of the resonances agree well with available results. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. We find that the polarization has a substantial effect on the cross sections, and this effect becomes even more important for lower impact energies.     

Accurate calculation of the elastic scattering properties of ^7Li atoms at ultralow temperatures

The elastic scattering properties for collisions between two ^7Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X^1 ∑g^＋ and triplet a^3 ∑u^＋ ground states of the Li2, Our calculated values for the scattering lengths α and the effective ranges re are compared with previous ones, and found them to be in good agreement. The scattering lengths are 34.6α0 for the singlet state and -27.6α0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X^1 ∑g^＋ and a^3 ∑u^＋ states.     

低能电子与N2分子碰撞的振动共振激发散射截面的密耦合研究

使用经孙卫国教授改进后的振动密耦合散射方法和基于量子力学从头计算得到的静电、交换与极化散射作用势,研究了低能电子与N2分子的振动激发散射截面.研究表明在振动密耦合计算中使用18个振动波函数和12个分波数目,可以得到收敛的0→5,1→5等高激发散射的积分和微分截面.     

用振动密耦合方法研究低能电子与N2分子碰撞的振动激发微分散射截面

采用振动密耦合方法，分别应用球高斯分布极化势和优于绝热极化势，及基于量子力学从头计算的静电、交换势，得到入射电子能量2.40eV时0→2和0→3的振动激发微分散射截面，与目前优秀的实验值比较，获得了满意的结果，并从理论上分析了整个计算过程中可能影响微分散射截面精度的主要物理因素.     

用振动密耦合方法研究低能电子与N2分子碰撞的振动激发微分散射截面

采用振动密耦合方法,分别应用球高斯分布极化势和优于绝热极化势,及基于量子力学从头计算的静电、交换势,得到入射电子能量2.40eV时0→2和0→3的振动激发微分散射截面,与目前优秀的实验值比较,获得了满意的结果,并从理论上分析了整个计算过程中可能影响微分散射截面精度的主要物理因素. 关键词： 分子碰撞 微分散射截面 振动激发 相互作用势     

Elastic scattering of two ground-state N atoms

An interaction potential for an N₂(X¹σ_g⁺) molecule is constructed by using the highly accurate valence internally contracted multireference configuration interaction method and the largest basis set, aug-cc-pV6Z, in the valence range. The potential is used to investigate the elastic scattering of two N atoms at energies from 1.0× 10^-11 to 1.0× 10^-4 a.u. The derived total elastic cross sections are very large and almost constant at ultralow temperatures, and the shape of total elastic cross section curve is mainly dominated by the s-partial wave at very low collision energies. Three shape resonances are found in the total elastic cross sections. Concretely, the first one is very sharp and strong. It results from the g-partial-wave contribution and the resonant energy is 3.645× 10^-6 a.u. The second one is contributed by the h-partial wave and the resonant energy is 1.752× 10^-5 a.u. This resonance is broadened by those from the d- and f-partial waves. The third one comes from the l = 6 partial wave contribution and the resonant energy is 3.522× 10^-5 a.u. This resonance is broadened by those from the g- and h-partial waves. The N₂(X¹σ_g⁺) molecular parameters, which are determined at the current theoretical level, achieve very high accuracy due to the employment of the largest correlation-consistent basis set in the valence range.     

超低温下钠原子散射特性研究

超低温下钠原子的散射特性对原子间的相互作用势非常敏感.本文基于构造精确的原子间相互作用势,详细研究了在超冷温度下处在超精细态|F=2,mF=2〉下23Na原子的弹性散射特性.我们分别用Numerov和半经典方法计算了散射长度和有效程,得到了较满意的结果.低能散射截面有丰富的共振现象产生,我们发现并给出了d-波和g-波形状共振的能级位置和共振宽度;此外,我们还对仅两个分波有贡献情况下的微分散射截面进行了理论计算.     

超冷温度下钾和铯原子间弹性散射特性的精确计算

本文分别用量子方法和半经典方法计算了超冷钾和铯原子之间弹性碰撞的s波散射长度,有效力程和p波散射长度等散射参数. 超冷温度下³⁹K-¹³³Cs原子间的弹性散射截面主要为s波贡献,随着碰撞能量的增加散射截面有丰富的形状共振出现, 计算发现单重态和三重态截面分别存在显著的g波和d波形状共振.另外,本文应用简并内态近似方法获得了⁴¹K-¹³³Cs 超精细态相互作用时的s波散射长度.