切实加强学科建设构筑高校核心竞争力

学科是高校发挥教学、科学研究和社会服务三大功能的基本平台,学科水平是学校办学水平和综合实力的主要体现。学科建设主要是指围绕提高学科水平所做的一系列基础性工作,学科建设水平是高校整体竞争力中最重要的核心部分即核心竞争力一要从构筑核心竞争力的高度来认识加强学科建设对高校发展的重大意义,用教育创新的工作思路落实建设的具体措

Electronic Structure of β-KSi_3N_4

用局域密度泛函理论和lMTO-ASA方法计算了氮化硅β-SI3n4的电子结构。由于采用了lOWdIn微挠理论，在保证能量精度的条件下，大大减少了计算工作量。通过三种不同空原子球设置方案的能带计算结果的比较，详细讨论了在开结构晶体能带计算中的空原子球设置（包括空原子球的数目，位置和半径）对能带的影响。结果表明，空原子球的合理设置对于得到正确开结构材料的能带结构，特别是导带结构是重要的。本文结果和第一原理赝势法得到的能带相吻合。Electronic structure of silicon nitride,β-Si3N4,was calculated by local density Functional theory and LMTO-ASA method cooperated with the use of Lowdin perturbation technique that saved computation time considerably and insured the computation accuracy.On the bases of calculated energy bands From the three diFFerent settings of the empty atomic spheres,the eFFects of setting (e.g.the number,positions and radius of the empty atomic spheres)on the energy band were discussed in details.It has been shown that the reasonable setting of empty atomic spheres is important For the widely opened crystal structures to obtain the correct energy band,especially correct conduction band.The energy band of the presented calculation is in good agreement with that of the ah initio pseudopotential calculation.中国科学院上海硅酸盐研究所高性能陶瓷和超微结构开放实验室资

Researches on the Phenomena of Bose-Einstein Condensation(BEC)

玻色 -爱因斯坦凝聚 (BEC)的研究是当前物理学研究的一个新热点 ,国内外许多学者都开展了研究 .为探讨有关 BEC的普遍性质和规律以及影响 BEC的主要物理因素 ,我们研究了任意空间维数下 ,处于任意幂函数型外势约束中具有不同运动特征的玻色气体和费米气体的性质 .导出量子态密度、巨势及其它热力学函数的普遍解析表达式 ,提出赝体积和普遍热波长等新概念 ,首次求得有外势约束的玻色气体的态方程 ,并揭示了 BEC的一些新性质和确立了有关 BEC的两个新判据 ,同时还发现了 N0 / N～ T/ TC 曲线必为凸型的新规律 ,等等 .所得结果有助于深入了解 BEC这种新物态的特性 ,并为实验选择最佳外势阱的形式及其它物理参数提供一些新的理论依据 .此外还简要地介绍了国内外研究动态与进展以及本研究的前景 .At present, the study on Bose Einstein condensation(BEC) has become a new hot point in physical researches. There are many scholars who have carried out researches at home and abroad in this area. In order to explore the general properties and laws of BEC and study how the properties of BEC depend on the physical parameters, we consider an ideal Bose or Fermi gas trapped in a generic power law potential in any dimensional space with a general dispersion relation. The universal analytical expressions of the density of states, grand potential and the other thermodynamic functions of the system were derived. The new concepts of the pseudovolume and general thermal wavelength were introduced, and the equation of state of the trapped Bose gas was derived for the first time. Moreover, two new criteria about BEC were established and some new laws, such as the curve of N 0/N～T/T c are always convex for Bose system in BEC phase, and so on, were found. All these results are useful for deep understanding the properties of the new matter state of BEC. On the basis of our results, the possibility of controlling the critical temperature and properties of BEC through setting up some physical parameters to facilitate the realization of BEC is exciting. In addition, the recent developments in BEC investigation and the prospects for BEC are introduced simply in this paper.国家教委跨世纪优秀人才培养计划基金;; 福建省自然科学基金!(A970 10 )资助项

Chemical Potential and Heat Capacity of an Ideal FermiGas Trapped in a Harmonic Potential in any Dimensional Space

采用THOMAS-fErMI的半经典近似方法，得到处于n维空间简谐势阱中的理想费米气体的化学势和热容量等物理量的通用表示式，并讨论了空间维数和外势对这些物理量的影响The general analytical expressions of chemical potential and heat capacity of an ideal Fermi gas trapped in a harmonic potential in any dimensional space are derived by using the semiclassical (ThomasFermi) approximation.How these physical quantities depend on the external potential and the dimension of space are discussed.福建省自然科学基

The Density of States of Particles in a Harmonic Potential in Any Dimensional Space

应用半经典近似法计算任意维数非相对论性理想体系处于简谐外势中的量子态密度，得出解析的表达式，并进行讨论.揭示了简谐外势对系统性质的影响.特别是对于二维系统，使之从准长程序转变为长程序，对于一维系统，使之从无序转变为准长程序By Using the semi classical approximation, the density of quantum states of the nonrelativistic ideal system in a harmonic potential is calculated, and the analytical results are derived For any dimensional systems.The eFFects of harmonic potential on the properties of such systems are expounded.It is shown that the eFFect of harmonic potential on the low dimensional system is quite evident, which makes the two dimensional system From quasi long range order to long range order and the one dimensional system From disorder to quasi long range order.福建省自然科学基

Bose-Einstein Condensation(BEC) of n Dimensional Ideal Bose Gas in External Potential

自从1995年人类首次实现了70年前爱因斯坦所预言的玻色-爱因斯坦凝聚(bEC)以来,有关bEC的理论研究成为物理学界的一个新热点,爱因斯坦所预言的bEC是对理想玻色气体而言的,尽管实际气体的原子间有互作用,但对稀薄气体,这种互作用是微弱的、一些计算表明,其结果与理想气体相比仅差约0.4%.因此,作为计算的初级近似,可将玻色气体视为理想的.福建省自然科学基金资助项

Studying of Static Properties of B1 WC and Bl-MoC Crystals by LMTO ASA Method

【中文摘要】 本文用LMTO-ASA方法和局域密度泛函理论,从第一原理计算了BI结构的WC和MoC晶体的总能-体积曲线.由此求得WC和MoC晶体的平衡晶格常数分别为0.420nm和0.416nm,体弹性模量分别为5(±10％)Mbar和4(±10％)Mbar,与已有实验很好符合.结果表明,在总能计算中计及对静库仑相互作用能的Ewald修正,对理论结果有明显的改善. 【英文摘要】 In this paper, the total energy curves of B1-WC and Bl MoC ciystals as a function of relative volume have been calculated by the LMTO ASA me thod based on the local density functional theory obtained from the first principle. The results have been used for the evaluations of the equilibrium lattice constants, which are 0.420 nm and 0.416 nm, and of the bulk moduli, which are 5(±10%) Mbar and 4(±10%) Mbar for WC and MoC crystal respectively. The theoretical results are in good argreement with the available e...中国科学院基