Ab initio investigations of the charge transport properties of endohedral M@C20（M=Na and K）metallofullerenes

Using density functional theory and quantum transport calculations based on nonequilibum Green’s function formalism,we investigate the charge transport properties of endohedral M@C 20 (M=Na and K) metallofullerenes.Our results show that the conductance of C 20 fullerene can be obviously improved by insertion of alkali atom at its centre.Both linear and nonlinear sections are found on the I-V curves of the Au-M@C 20-Au two-probe systems.The novel negative differential resistance behaviour is also observed in Na@C 20 molecule but not in K@C 20.     

边界振动的微腔中的二能级原子

采用全量子理论，对注入腔内的二能级原子、单模腔场和振动边界(视为频率为ω_m的量子谐振子)构成的系统，在相互作用绘景中，求解了该系统的态函数随时间的演化关系，在此基础上得到了原子布居数随时间的演化关系，结果显示布居数在初始值附近振荡，这说明边界的振动是周期性的，它对原子布居数的影响也是周期性的. 关键词： 边界振动的微腔 二能级原子 布居数     

Potential energy curve study on the ^3Π electronic states of GaX （X=F,Cl, and Br） molecules

The potential energy curves （PECs） of the 3Π states of GaX （X=F, Cl, and Br） molecules are calculated using the multireference configuration interaction method with a large contracted basis set aug-cc-pV5Z. The PECs are accurately fitted to analytical potential energy functions （APEFs） using the Murrell–Sorbie potential function. The spectroscopic parameters for the states are determined using the obtained APEFs, and compared with the theoretical and experimental data available presently in the literature.     

平均速度近似为瞬时速度造成系统误差的多方法研究——以倾斜气垫导轨法测量重力加速度实验设计为例

匀变速直线运动加速度计算公式应用中,最基本的物理观念是几个物理量之间存在着“一一对应”关系。在倾斜气垫导轨法测量重力加速度实验中,滑块运动的瞬时速度无法准确测量,只能用平均速度代替,造成了公式应用中要求的物理量之间的“一一对应”关系被破坏,产生了无法克服的系统误差。本文设计了匀加速和匀减速直线运动两种实验情境,分别用控制变量法、数学解析法和图像法等多种方法研究了不同实验情境的系统误差,将系统误差分析与物理观念构建建立了联系,分析了挡光片宽度d、加速情境滑块静止释放时离第一个光电门的距离L、减速情境滑块静止时离第二个光电门距离M、两光电门间距S和气垫导轨倾角θ等参量对该系统误差的影响,研究表明：d、S、L或W参量对该系统误差都有影响;d值的大小是造成该系统误差的主要因素;θ参量无影响;应用公式(1)计算重力加速度值更精确。     

改性聚酯异形中空微孔纤维性能研究

利用不同的异形喷丝板,将聚对苯二甲酸乙二酯(PET)与不同间苯二甲酸- 5- 磺酸基团摩尔含量的共聚酯(HCDP)共混纺丝,制得一系列改性聚酯纤维.改性纤维的断裂强度随共混HCDP中磺酸基团摩尔含量的增加呈现下降趋势,但该趋势在磺酸基团含量达到一定数量后出现回升.纤维对阳离子染料的吸收率随磺酸基团摩尔含量的增加而增加,但对分散染料而言此差异较小,并且不论何种染料,纤维横截面的变化对上染率的影响均不明显.碱处理对纤维上染率影响巨大.纤维保水率与纤维碱处理后形成的具有毛细效应的微孔结构以及异型纤维本身形成的毛细结构有密切关系,而且纤维对水分的传输性能在很大程度上取决于纤维的横截面形状,纤维碱处理后形成的微孔特别是透孔结构有助于输水性能的改善.     

A full-dimensional analytical potential energy surface for the F+CH_4→HF+CH_3 reaction

A full-dimensional analytical potential energy surface(APES) for the F + CH4 →HF + CH3 reaction is developed based on 7127 ab initio energy points at the unrestricted coupled-cluster with single,double,and perturbative triple excitations.The correlation-consistent polarized triple-split valence basis set is used.The APES is represented with a many-body expansion containing 239 parameters determined by the least square fitting method.The two-body terms of the APES are fitted by potential energy curves with multi-reference configuration interaction,which can describe the diatomic molecules(CH,H2,HF,and CF) accurately.It is found that the APES can reproduce the geometry and vibrational frequencies of the saddle point better than those available in the literature.The rate constants based on the present APES support the experimental results of Moore et al.[Int.J.Chem.Kin.26,813(1994)].The analytical first-order derivation of energy is also provided,making the present APES convenient and efficient for investigating the title reaction with quasiclassical trajectory calculations.     

Dynamic mechanism for encapsulating two HIV replication inhibitor peptides with carbon nanotubes

Encapsulation of biomolecules inside a carbon nanotube(CNT) has attracted great interest because it could enable the delivery of nanoscale pharmaceutical drugs with CNT-based devices.Using a molecular dynamics simulation,we investigate the dynamic process by which human immunodeficiency virus(HIV) replication inhibitor peptides(HRIPs) are encapsulated in a water solution contained inside a CNT.The van der Waals attraction between the HRIPs and the CNT and the root-mean-square deviation are used to analyse the evolution of the encapsulation.It is found that the interaction between the HRIPs and the CNT is the main driving force for the encapsulation process,which does not cause an obvious conformational change to the HRIPs.     

Si6X(X=Cu,Ag,和Au)团簇多激子产生的从头算研究

利用对称性组态相互作用理论（SAC-CI）和LANL2DZ基组研究Si₆X（X=Cu、Ag和Au）团簇的多激子产生（MEG）.在团簇的MEG计算之前,基于密度泛函理论和全电子基组DZP-DKH,对团簇的几何结构进行优化并且经过频率分析确认团簇的能量稳定性.结果表明：多激子的主导成分是双激子,这些团簇的MEG都出现在可见光范围内,团簇的MEG强的部分在紫外线范围内,为利用MEG制备光俘获材料提供信息.     

深基坑支护设计浅探

深基坑支护的设计、施工、监测技术是近10多年来在我国逐渐涉及的技术难题。深基坑的护壁,不仅要求保证基坑正常作业安全,而且要防止基坑及坑外土体移动,保证基坑附近建筑物、道路、管线的正常运行。各地通过工程实践与科研,在基坑支护理论与技术上都有了进一步的发展,取得了可喜的成绩。     

平抛运动演示仪的创新与自制

现有的平抛运动演示仪存在实验现象不直观、操作繁琐耗时长、器材昂贵等缺点,因此,选择生活中常见的器材自制教具.巧妙地利用联动装置保证了小球同时运动,生动形象地演示平抛运动在水平和竖直方向的运动情况,同时利用磁性小球和磁性画板描绘其运动轨迹.能使学生直观明了地观察到做平抛运动的物体的运动轨迹,同时教具操作简单方便,经久耐用.