Ne-CH4分子间相互作用势的局域密度近似计算

利用基于密度泛函理论框架下的局域密度近似方法对Ne-CH4分子间的相互作用势进行了计算. 发现: 当Ne原子和CH4分子之间的距离约为5.8 a.u.时, 计算的势能曲线存在最小值, 对应的势阱深度约为0.053 eV. 计算结果与实验值符合较好.     

低密度氢气的分子间平均相互作用势理论和计算

本文提出了分子单中心模型,并通过对构型的平均,两个定理的提出与证明,色散能修正的证明,从数学上论证了这个模型的合理性。由此模型可以直接求出两个氢分子间的平均相互作用势,从而改变了长期以来,总是先算有限几种构型然后再作平均的传统作法。通过数字计算,得到了迄今为止最好的全程平均相互作用势曲线。势阱深度及平衡分子间距分别为-2.91meV和3.44(实验值:-2.85～-3.00meV,3.43～3.49)。     

Ne-CH4分子间相互作用势的局域密度近似计算

利用基于密度泛函理论框架下的局域密度近似方法对Ne-CH4分子间的相互作用势进行了计算. 发现 当Ne原子和CH4分子之间的距离约为5.8 a.u.时, 计算的势能曲线存在最小值, 对应的势阱深度约为0.053 eV. 计算结果与实验值符合较好.     

叠氮乙烷二聚体分子间相互作用的理论研究

用abinitioHF/ 6 3 11+ +G 计算求得叠氮乙烷二聚体势能面上三种优化构型和电子结构 .经MP2电子相关校正和基组叠加误差 (BSSE)以及零点能 (ZPE)校正 ,求得分子间最大相互作用能为 -10 .45kJ/mol.二子体系间的电荷转移很少 .由自然键轨道 (NBO)分析揭示了相互作用的本质 .基于统计热力学求得温度为 2 0 0 .0 0～80 0 .0 0K从单体形成二聚体的热力学性质变化     

TATB分子的结构及分子间相互作用

采用Hartree-Fock方法和密度泛函BPW91方法,对TATB双分子系统的几何结构和能量进行了优化和计算,得到双分子共平面的平衡结构.结果表明在TATB分子内部H和O之间存在着明显的氢键.分子之间的相互作用使TATB分子的对称性下降.一般地,没有充分计入分子之间的相互作用的影响时,计算得到的C-N键长比实验测得值大,而计算得到的C-C键长比实验测得值小.计算并讨论了TATB分子之间的相互作用能,表明TATB分子形成晶体结构时,应当以层状晶体结构最为稳定.     

C60分子之间相互作用势的Kihara形式

根据Ｃ６０－晶体的升华焓，晶包参数和压缩系数，求得了Ｃ６０分子之间相互作用势的Ｋｉｈａｒａ形式，并且讨论了简单的Ｌｅｎｎａｒｄ－Ｊｏｎｅｓ势不能很好地描述Ｃ６０分子之间的相互作用。根据Ｃ６０分子之间相互作用势的Ｋｉｈａｒａ形式，计算了不同Ｃ６０晶型的某些性质，讨论了Ｃ６０晶体不同晶型的稳定性问题。     

高密度氢气的分子间相互作用与状态方程

本文从高密度氢气的分子间相互作用出发进行分析,在修改范德瓦耳方程的基础上,提出了一种新的适用于高密度氢气的状态方程,并用来系统地计算了氢气在临界区的等温压缩线.在缺乏实验数据的情况下,这些理论计算结果很有用.     

高温高密度条件下氢分子间三体与四体相互作用

 为描述高温高密度条件下氢分子间复杂的多体相互作用，以Ree和Bender对两个氢分子间平均作用势的CI计算结果为基础，提出一种可以描述旋转氢分子外域电子云分布的等效氦原子模型。采用该模型所计算的氢分子三体势与CI计算结果符合较好。还对氢分子间四体势进行了计算。     

固体中的原子间相互作用势

近年来，原子间相互作用势广泛应用物理、化学、材料科学中，文章综合评述了金属和半导体中原子间相互作用势研究的发展状况以及各种势函数的范围和存在的总理２，总结了近年来金属合金以及半导体化合物中原子间相互作用势的应用情况，并讨论了固体中原子间相互作用势的发展方向。     

Modelling the interaction in a benzene dimer

The interaction between aromatic rings is a fundamental problem in material science and biochemistry. These interactions are generally found to stabilise protein molecules and the double helical structure of DNA, and they also play an important role in the recognition processes in biological and non-biological systems. However, the complexity and variety in the structures and components of aromatic compounds are major obstacles to investigating their interactions. In this study, the simplest case of aromatic interactions, which is the interaction between two benzene rings, is modelled using a continuous approximation. Assuming a constant atomic surface density and modelling the structure of a benzene molecule as a combination of two rings, namely an inner carbon ring and an outer hydrogen ring, the van der Waals interaction between any two benzene rings can be obtained as the sum of four interactions. The major result obtained here is an analytical expression for the potential energy which can then be used to predict equilibrium configurations for two interacting benzene molecules. Moreover, we find that at sufficiently large distances between the two benzene molecules, the orientational angle φ at which the interaction energy is a minimum can be approximated by the arctan of the ratio of two separation distances in two mutually perpendicular directions.     

A comparison of various approaches in internally contracted multireference configuration interaction: the carbon dimer as a test case

Various variational spaces deriving from different contraction schemes of the first-order interacting space have been examined and their performances have been tested on the carbon dimer. The contraction schemes stemming from the strongly contracted and from the partially contracted approach of the n-electron valence state perturbation theory have been analysed along with the mixed approach of Werner and Knowles as well as with the totally uncontracted approach where the full dimensionality of the first-order interacting space is taken into account. The results are very similar for all the spaces considered, despite their widely varying dimensionality. A comparison with the second-order and the third-order results of NEVPT is also reported.     

Anomalous atmospheric absorption spectra due to water dimer

The anomalous atmospheric absorption spectra in the window wavelength region of 8–14 um have been suggested due to the water dimer. Based on our laboratory measurements, water continuum CO₂ laser absorption spectra and a resonance absorption line due to the weak local water vapor pure rotational transition have been reported. The equilibrium concentration of water dimers in the atmosphere, the electronic binding energy and the theoretical calculations for absorption attenuation have been obtained in agreement with published data.     

A relativistic coupled-cluster interaction potential and rovibrational constants for the xenon dimer

An accurate potential energy curve has been derived for the xenon dimer using state-of-the-art relativistic coupled-cluster theory up to quadruple excitations accounting for both basis set superposition and incompleteness errors. The data obtained is fitted to a computationally efficient extended Lennard-Jones potential form and to a modified Tang–Toennies potential function treating the short- and long-range part separately. The vibrational spectrum of Xe₂ obtained from a numerical solution of the rovibrational Schrödinger equation and subsequently derived spectroscopic constants are in excellent agreement with experimental values. We further present solid-state calculations for xenon using a static many-body expansion up to fourth-order in the xenon interaction potential including dynamic effects within the Einstein approximation. Again we find very good agreement with the experimental (face-centred cubic) lattice constant and cohesive energy.     

Photoionization Cross Section and Resonance Structure of Mn+

A photoionization cross section calculation of Mn⁺ is performed in the formalism of many-body perturbation theory for photon energies ranging from 48 eV to 56 eV. We consider excitations from the 3p, 3d, and 4s subshells. The effects of the strong 3p→3d and 3p→4s transitions are included as resonant contributions to the total cross sections. Good agreement with experiment is found.     

形如Coulomb势的本征值微扰计算

用超位力定理(HVT)和赫尔曼-费恩曼(Hellman-Feynman)定理(HFT)计算了Coulomb势加上径向线性项和常数项的本征能量的微扰系数,这种计算方法优于通常的瑞利-薛定谔微扰理论,不需要计算本征函数系数,并且用这种方法可以既快捷又有效地计算大量本征能量的微扰系数.     

电子激发和溶剂效应对芴酮-甲醇分子间氢键增强现象的理论研究 (cited: 1)

理论研究了电子激发和溶剂效应导致的芴酮-甲醇复合体系中分子间氢键增强现象．通过基态和激发态性质的计算,不仅展示了分子间氢键键长的变化以及变化在振动光谱中的影响,而且揭示了导致氢键变化的内在物理机制：溶质分子的电子激发及溶剂化效应引起的电子重新分布,增大了溶质和溶剂分子的偶极矩,导致了它们之间的相互作用的增大,并最终加强了分子间氢键的强度．还分别对处于液相及气相中的复合体的基态和激发态的几何结构、红外谱、复合体及构成分子的偶极矩进行了理论计算,结果阐明了电子激发与溶剂化效应对氢键变化的贡献,同时还发现只有进一步引入溶剂化效应,复合体的基态、激发态的性质才能与实验达到精确一致．所有激发态均采用所开发的基于含时密度泛函理论解析计算一阶、二阶激发态能量导数的方法．