椭球坐标下求解强磁场中的氢原子

在椭球坐标系下,采用B样条基组方法计算了磁场范围在0-1000 a.u.下氢原子低能态能量以及实验室磁场下(几个特斯拉)氢原子里德堡态的能级,得到了至少9位有效数值的高精度能谱并与文献中的精确结果进行了比较.本文方法为精确计算强磁场下原子能谱提供了一个新的选择方案.     

椭球坐标下求解强磁场中的氢原子

在椭球坐标系下，采用B样条基组方法计算了磁场范围在0—1000 a．u．下氢原子低能态能量以及实验室磁场下（几个特斯拉）氢原子里德堡态的能级，得到了至少9住有效数值的高精度能谱并与文献中的精确结果进行了比较。本文方法为精确计算强磁场下原子能谱提供了一个新的选择方案。     

磁场中氢里德堡波包的自动关联函数

本文采用激光短脉冲激发磁场中氢原子,研究氢里德堡波包在磁场中随时间的演化.结果证实氢里德堡波包在磁场中的运动也与闭合轨道密切相关.讨论了脉冲宽度τ对自动关联函数的影响以及不同初始态下的自动关联函数.     

锂分子里德堡态和双激发态的重新分类

根据里德堡轨道的类氢nλ特性 ,对 7Li2 实验已观测到的和理论计算给出的 6 8个电子态进行了分类 ,把这些态划分为核实贯穿里德堡态和核实非贯穿里德堡态 .讨论了双电子激发态和里德堡态的微扰 ,也讨论了这种分类的意义     

长程铯里德堡分子的势能曲线

本文介绍了半经典近似下的低能电子-原子散射理论, 引入贋势描述里德堡电子与基态原子的相互作用, 数值计算了铯原子nS (n=30-60)里德堡态与6S基态原子形成的长程里德堡分子的势能曲线. 并对最外层势阱进行分析, 获得长程里德堡分子的势阱深度、平衡距离与主量子数n的关系. 为实验制备里德堡分子并进一步分析其性质提供理论依据. 里德堡分子对外界非常敏感, 可用于微弱信号的检测.     

F+H2→HF+H反应的全量子态分辨的散射动力学研究

利用高灵敏度的氢原子里德堡飞渡时间谱方法研究了 F H_2→HF H 反应碰撞能在5.02kJ/mol 下的交叉分子束反应态态散射动力学.所有在时间飞渡谱中被观测到的谱峰可以归属为 HF 产物的振转态结构.还观测到了明显的 HF(v’=3)前向散射,以及少许的 HF(v’=2)前向散射.     

理论研究强激光场中2pz态氢原子的电离

运用强场近似速度规范理论研究了激发态氢原子的电离情况,当ω1a.u.,γ1时(ω是激光场的频率,γ是Keldysh绝热参数),在线性极化激光场中推导了2pz态氢原子电离率的简单表达式,从公式中可以看出在低频极限的情况下,电离率和激光场频率ω成正比,这一公式对激发态氢原子电离机制的研究提供了重要的理论参考.     

高里德堡态氢原子与氦原子散射的高分辨研究

利用了氢原子飞渡时间谱实验方法对处于高n主量子数里德堡态的氢原子与氦原子的分子束散射过程进行了高分辨研究.测量了H(n)+He→H(n′)+He散射过程的散射微分截面.实验结果表明,产物主要分布在前向散射方向,在侧向也有一定的分布.在前向和侧向存在大量的振荡结构.同时详细的研究也表明,在上述的散射过程中往前散射的方向上,氢原子里德堡态主量子数n的变化并不是很大.实验结果得到了为理论上精确研究高n主量子数里德堡态的氢原子与氦原子的散射动力学的一套精细的实验数据.     

ns6s里德堡分子的势能曲线

里德堡电子与基态原子的低能电子散射形成长程里德堡分子,这种分子具有大的轨道半径,丰富的振动能级和永久电偶极矩等特点。本文考虑铯里德堡ns态与(n-4)l(n为主量子数,l为角量子数且l2)近简并态的非绝热耦合与p-波共振现象,数值计算了长程铯里德堡分子的势能曲线。分析ns6s(n=32-36)态分子最外层势阱,研究了长程里德堡分子的势阱深度、平衡距离与主量子数n的关系,为实验研究长程里德堡分子提供理论依据。     

理论研究强激光场中2pz态氢原子的电离

运用强场近似速度规范理论研究了激发态氢原子的电离情况,当 a.u. 时（ω是激光场的频率,γ是Keldysh绝热参数）,在线性极化激光场中推导了2pz态氢原子电离率的简单表达式,从公式中可以看出在低频极限的情况下,电离率和激光场频率ω成正比,这一公式对激发态氢原子电离机制的研究提供了重要的理论参考。     

Hydrogen atom in strong magnetic field: a high accurate calculation in spheroidal coordinates

A B-spline-type basis set method for the calculation of hydrogen atom in strong magnetic fields in the frame of spheroidal coordinates has been introduced. High accurate energy levels of hydrogen in the magnetic field, with strength ranging from 0 to 1000 a.u., have been obtained. For the ground state, 1s₀, energies with at least 11 significant digits have been obtained. For the low-lying excited state, 2p₋₁, energies with at least 9 significant digits are obtained. The method has also been applied to the calculation of hydrogen Rydberg states in laboratory magnetic fields. Energy spectra with at least 10 significant digits are presented. A comparison with other results in the literatures has been performed. Our results are comparable to the most accurate one up to date. A possible extension to the cases of parallel and crossed electric and magnetic fields have been discussed.     

磁场对异质界面上D-中心的影响

势阱中的类氢杂质的能级问题一直为学术界所长期关注。讨论了异质界面上中性施主D⁰和负施主离子D^-的能量随垂直于界面的磁场的变化情况,同时将磁场和势阱结合起来考虑其对类氢杂质的影响。研究发现随磁场的增大,其对D⁰基态能的影响越来越大,对其束缚能的影响逐渐变小,而对D^-中心,磁场的作用使得D^-由非束缚态转变为束缚态。计算中分别选取了两种不同的波函数,分析了这两种波函数的适用范围,利用变分的方法得到此结构中D⁰中心的基态能量和束缚能与D^-中心角动量L=-1自旋三重态的本征能量和束缚能随磁场的变化关系,找到了此三重态由非束缚态转变到束缚态对应磁场的阈值。     

强磁场中氢原子的能级结构

发展了一套简单高效的非微扰理论方法研究强磁场中的原子能级结构.作为例子,给出了磁场强度从0到1000个原子单位,氢原子基态和低激发态的结合能以及四极矩等重要原子能级结构参数.结果表明:相对于其他的高精度计算方法,该方法不仅能计算出高精度的能级位置而且可方便给出精确的电子波函数.此外,该法还具有很强的普适性,可直接推广到原子与任意方向的交叉电磁场相互作用的研究. 关键词： 强磁场 CWDVR谱方法 氢原子能级结构 四极矩     

Ground states of the hydrogen molecule and its molecular ion in the presence of a magnetic field using the variational Monte Carlo method

ABSTRACT

By using the variational Monte Carlo (VMC) method, we calculated the 1sσ_g-state energies, the dissociation energies, and the binding energies of the hydrogen molecule and its molecular ion in the presence of an aligned magnetic field regime between 0 and 10?a.u. The present calculations are based on using two types of compact and accurate trial wave functions, which are put forward for consideration in calculating energies in the absence of a magnetic field. The obtained results are compared with the most recent accurate values. We conclude that the applications of the VMC method can be successfully extended to cover the case of molecules under the effect of a magnetic field.     

Xe-NH (X3∑-)体系的势能面和冷碰撞动力学研究

以超冷Xe原子感应冷却NH（X³∑^-）分子实验为背景,理论研究磁场中Xe和NH的冷碰撞动力学性质.通过从头算方法得到了解析表达的Xe-NH体系势能面,并在此基础上采用量子动力学计算方法,研究了磁场条件下NH低场追索态（n=0,m_j=1）的冷碰撞塞曼弛豫截面.结果表明超冷Xe原子感应冷却NH分子可能在实验上难以实施.     

Polarization operator of a photon in a magnetic field

The polarization operator of a photon in a static uniform magnetic field has been studied at photon energies both above and below the threshold of electron–positron pair production by a photon. In the first order of the fine-structure constant α, expressions for the refractive index of a photon with a certain polarization in both low and high fields as compared to the critical field H₀ = 4.41 × 10¹³ G have been obtained. Both the purely quantum range of photon energies, where the particles of a pair are produced at the lowest Landau levels, and the region of applicability of the semiclassical approximation in the case of the population of high energy levels have been considered. A general spectral integral formula has been obtained with divergent threshold terms separated in an explicit form.     

Positronium formation for positron scattering from metastable hydrogen

Positronium(Ps) formation for positron impact on metastable hydrogen in 2s state has been studied by using the twochannel, two-center eikonal final state-continuum initial distorted wave(EFS-CDW) method. The differential, integrated,and total cross sections for Ps formation in different states have been calculated from each channel opening thresholds to high energy region. The results are compared with other theoretical calculations available in the literature. For Ps formation in s-state at intermediate and high energies, our results are in good agreement with the prediction of distorted wave theory.Those formed in p-states and the total Ps formation cross sections are reported for the first time. It is shown that the total Ps formation cross sections for positron scattering from H(2s) state are significantly larger at relatively low energies, while smaller at high energies, compared with those obtained from hydrogen in ground state.     

Accurate calculations of the helium atom in magnetic fields

The 1 1 0 +,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-Gaussian 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.     

Broadband radiation transport in an optically dense gas in the presence of an RF field

The variational Monte Carlo method is applied to investigate the ground state and some excited states of the lithium atom and its ions up to Z = 10 in the presence of an external magnetic field regime with γ = 0–100 arb. units. The effect of increasing field strength on the ground state energy is studied and precise values for the crossover field strengths were obtained. Our calculations are based on using accurate forms of trial wave functions, which were put forward in calculating energies in the absence of magnetic field. Furthermore, the value of Y at which ground-state energy of the lithium atom approaches to zero was calculated. The obtained results are in good agreement with the most recent values and also with the exact values.     

Simulated Annealing for Ground State Energy of Ionized Donor Bound Excitons in Semiconductors

We present a global optimization method, called the simulated annealing, to the ground state energies of excitons. The proposed method does not require the partial derivatives with respect to each variational parameter or solving an eigenequation, so the present method is simpler in software programming than the variational method,and overcomes the major difficulties. The ground state energies of ionized-donor-bound excitons (D^ ,X) have beencal culated variationally for all values of effective electron-to-hole mass ratio σ. They are compared with those obtained by the variational method. The results obtained demonstrate that the proposed method is simple, accurate, and has more advantages than the traditional methods in calculation.