甲烷晶体的晶格能和弹性性质: 不同方法及泛函的评估

通过对甲烷晶体进行结构、晶格能和弹性特性的研究, 评估了不包含和包含色散能量修正的密度泛函理论的性能. 我们分别利用不包含色散能量修正的密度泛函理论(DFT) (包含不同的标准泛函和杂化泛函)和包含色散能量修正的密度泛函理论(DFT-D)计算了甲烷晶体特性, 并与实验作对比. 尽管DFT-D 与传统密度泛函理论及杂化密度泛函理论相比, 修正了甲烷晶体中的范德华(vdW)相互作用, 但是一些修正方案过分修正了这种相互作用. 因此, 人们在使用DFT-D方法时务必谨慎.     

CdTe和HgTe电子结构的紧束缚模型计算

基于局域密度近似(LDA或GGA)的密度泛函理论计算往往低估体系的禁带宽度,而这一低估对窄带隙半导体尤为严重.尽管基于混合泛函的密度泛函理论能有效地修正这一误差,但是由于计算量较大仍无法用于计算较大体系.本文发展了一组能够比较准确描述CdTe和HgTe晶体电子结构的紧束缚参数.将基于混合泛函的密度泛函计算结果作为输入,我们构建了正交的sp~3s~*基组下的紧束缚模型.此模型能够比较准确地描述能带结构在费米面附近4 eV范围内的色散关系.利用当前模型计算了CdTe和HgTe非晶的电子态密度,计算结果与他人的理论计算和实验值符合较好.     

纳秒激光烧蚀铝材料的二维数值模拟

为了探索纳秒脉冲强激光与材料的相互作用机理,建立了二维数值模型,利用有限差分法对纳秒激光脉冲烧蚀金属铝的温度场进行了数值模拟.通过对比不同脉宽、光斑和能量下激光引起的温度场随时间的演化,发现脉冲的前期温度升高比后期快.等温图显示中心温度升高最快,烧蚀轮廓与激光束形状相似,烧蚀深度达1—5 μm.脉宽越长,烧蚀越窄和越深,光斑越大,烧蚀越宽和越浅.数值研究表明,1)激光的脉冲形状、脉宽和功率密度直接影响烧蚀的形状和深度,2)激光功率密度在10⁹ W/cm²量级烧蚀     

笼状金团簇的休克尔模型研究

这篇文章分别用简单和扩展休克尔模型处理四种具有较大尺寸的笼状Au团簇（Au32,Au42,Au50,Au72）,这四种团簇经理论计算预言具有较高的稳定性. 将两种休克尔模型计算得到的能级分布,最高占据分子轨道(HOMO)与最低未占据分子轨道（LUMO）之间能隙,以及平均结合能与密度泛函理论的计算结果进行比较,探讨了采用休克尔模型研究笼状Au团簇的适用性,进而讨论了这些笼状团簇的球形芳香性.     

Unreacted equation of states of typical energetic materials under static compression:A review

The unreacted equation of state(EOS) of energetic materials is an important thermodynamic relationship to characterize their high pressure behaviors and has practical importance. The previous experimental and theoretical works on the equation of state of several energetic materials including nitromethane, 1,3,5-trinitrohexahydro-1,3,5-triazine(RDX),1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane(HMX), hexanitrostilbene(HNS), hexanitrohexaazaisowurtzitane(HNIW or CL-20), pentaerythritol tetranitrate(PETN), 2,6-diamino-3,5-dinitropyrazine-1-oxide(LLM-105), triamino-trinitrobenzene(TATB), 1,1-diamino-2,2-dinitroethene(DADNE or FOX-7), and trinitrotoluene(TNT) are reviewed in this paper. The EOS determined from hydrostatic and non-hydrostatic compressions are discussed and compared. The theoretical results based on ab initio calculations are summarized and compared with the experimental data.     

Enhanced Ferromagnetism of CrI_3 Bilayer by Self-Intercalation

Two-dimensional(2D) ferromagnets with high Curie temperature have long been the pursuit for electronic and spintronic applications.CrI₃ is a rising star of intrinsic 2D ferromagnets, however, it suffers from weak exchange coupling.Here we propose a general strategy of self-intercalation to achieve enhanced ferromagnetism in bilayer CrI₃.We show that filling either Cr or I atoms into the van der Waals gap of stacked and twisted CrI₃ bilayers can induce the double ...     

Coexistence of Zero-Dimensional Electride State and Superconductivity in AlH2 Monolayer

Elect rides,which confine "excess anionic electrons" in subnanometer-sized cavities of a lattice,are exotic ionic crystals.We propose a non-stoichiometric strategy to realize intrinsic two-dimensional(2D) superconducting elect ride.AlH₂ monolayer,which is structurally identical to 1H-MoS₂,possesses zero-dimensionally confined anionic electrons in the interstitial sites of A1 triangles,corresponding to a chemical formula of [AlH₂]⁺e^-.The inte...