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。     

碳分子线基态特性理论研究

从第一原理出发，利用密度泛函理论B3LYP系统研究了碳分子线Cn（n=3～10）的电子结构特性．对优化结果分析发现，由于离域效应的作用，当n为奇数时，分子线基态为单重态，反之，当n为偶数时，三重态为其稳定的基态．对其电子结构分析可得，随着n的增加，体系能量逐渐降低；同时本文确定了分子线体系最高占据轨道HOMO能量E^H、最低未占据轨道LUMO能量E^L与n的关系式，即En-2^H〈En^H〈En＋2^H，En-2^L〉En^L〉En＋2^L，因而碳分子线的费米能级会表现出特有的奇偶性．该工作将有利于准确认识分子器件的伏安特性，设计出良好性能的分子器件。     

H+,He2+与Li原子碰撞中电子俘获总截面的程函近似计算

采用Li原子价电子的有效势对前置形式程函近似振幅公式进行了修正,提出有效势修正程函近似方法,并对H^＋和He²⁺与Li原子碰撞中的电子俘获总截面进行了计算,取得了与实验比较吻合的结果. 关键词：     

Density Functional Calculations of C–NO_2 Bond Dissociation Energies for Nitroalkanes Molecules

Bond dissociation energies for the removal of nitrogen dioxide group in some nit- roalkane energetic materials have been calculated by using the three hybrid density functional theory (DFT) methods B3LYP, B3PW91 and B3P86 with 6-31g** and 6-311g** basis sets. The computed BDEs have been compared with the available experimental results. It is found that the B3P86 method with 6-31g** and 6-311g** basis sets can obtain satisfactory bond dissociation energies (BDEs), which are in extraordinary agreement with the experimental data. Considering the smaller mean absolute deviation and maximum difference, the reliable B3P86/6-311g** method was recommended to compute the BDEs for the removal of nitrogen dioxide group in the nitroalkane energetic materials. Using the method, the BDEs of 8 other nitroalkane energetic materials have been calculated and the maximum difference from experimental value is 1.76 kcal·mol-1 (for the BDE of tC4H9–NO2), which further proves the reliability of B3P86/6-311g** method. In addition, it is noted that the BDEs of C–NO2 bond change slightly for main chain nitroalkane compounds with the maximum difference of only 3.43 kcal mol-1.     

频率啁啾脉冲下里德堡锂原子量子态布居跃迁

采用含时多态展开方法(TDMA),结合B样条技术,计算了频率啁啾脉冲激光场中里德堡锂原子五个量子态之间的跃迁情况,并分析了激光场的四个主要参数对跃迁的影响.结果表明当取合适的激光参数时,可以实现布居数在量子态间的有效跃迁,从而一定程度上可以实现量子态的人工控制.     

锂原子的高激发态能级计算及其在微波场中的布居动力学过程

利用B样条技术,设计了一种计算高激发原子能级结构的方法,计算了高激发锂原子的能级结构,并研究了里德堡锂原子在微波场中的布居动力学过程。     

Coherent Control of Population Transfer in Li Atoms via Chirped Microwave Pulses

We demonstrate theoretically that Li atoms can be transferred to states of a lower principal quantum number by exposing them to a frequency chirped microwave pulse. The population transfer of Li atoms from the n = 75 state to n = 70 with more than 90% efficiency is achieved by means of the sequential single-photon △n = -1 transitions. The calculation fully utilizes all of the available orbital angular momentum l states for a given n, and the interference pattern and population evolution dynamics of individual l states are analyzed in detail. Using the time-dependent multilevel approach, we describe the process reasonably well as a sequence of adiabatic rapid passages.     

Theoretical Study of Elastic Properties of Tungsten Disilicide1

The plane-wave pseudopotential method using the generalized gradient approximation within the framework of density functional theory is applied to analyse the lattice parameters, elastic constants, bulk moduli, shear moduli and Young＇s moduli of WSi2. The quasi-harmonic Debye model, using a set of total energy versus cell volume obtained with the plane-wave pseudopotential method, is applied to the study of the elastic properties and vibrational effects. The athermal elastic constants of WSi2 are calculated as a function of pressure up to 35 GPa. The relationship between bulk modulus and temperature up to 1200 K is also obtained. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs function. The calculated results are in good agreement with the experimental data.