Exchange-correlation errors at harmonic and anharmonic orders: the case of bulk Cu

As an aid towards improving the treatment of exchange and correlation effects in electronic structure calculations, it is desirable to have a clear picture of the errors introduced by currently popular approximate exchange-correlation functionals. We have performed ab initio density functional theory and density functional perturbation theory calculations to investigate the thermal properties of bulk Cu, using both the local density approximation (LDA) and the generalized gradient approximation (GGA). Thermal effects are treated within the quasiharmonic approximation. We find that the LDA and GGA errors for anharmonic quantities are an order of magnitude smaller than for harmonic quantities; we argue that this might be a general feature. We also obtain much closer agreement with experiment than earlier, more approximate calculations.     

Electronic properties of magnetically doped nanotubes

Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons of the tube screen the magnetization of the dopants: the coupling to the tube is usually antiferromagnetic (except for Cr).     

RFA—300型自动分析仪检测总植物碱的改进

对连续流动法测定烟草及烟草制品中总植物碱的各影响因素进行了试验研究,并根据试验结果对仪器管路进行相应的改造。实验结果表明,烟草制品中总植物碱的连续流动法测定,改进后方法的回收收率高、重现性好。     

海拉尔盆地的古河道砂体识别方法

本文基于海拉尔盆地贝尔凹陷西北部高精度三维地震资料,通过对时间域、频率域地震属性的分析,研究了河道砂体的变化及分布规律,总结出了一套利用时间域、频率域地震属性识别古河道的方法。其中对河道砂体较为敏感的沿层属性主要有均方根振幅、反射强度梯度、有效带宽及瞬时频度等。利用这种识别方法在该区找到水下分流河道砂体和河口坝砂体,为该区的岩性勘探部署提供了具体目标。     

三峡工程三期截流三维施工仿真研究

三峡工程三期截流提前到 2 0 0 2年 11月上旬进行 ,截流难度显著增大。为了使截流工程顺利进行 ,以先进的计算机可视化技术为基础 ,采用IMAGIS软件生成三维地形图 ,用Creator建模形成导流明渠、纵向围堰及三期围堰等三维实体模型 ,最后通过运用虚拟现实技术 ,开发出三峡工程三期截流施工实时动态演示、查询系统。该系统能根据需要实现漫游 ,可以随意定位到感兴趣的区域作细部观察 ,且具有良好的交互性。通过施工仿真研究 ,将三期截流施工过程生动地显示在屏幕上 ,用以指导施工组织管理 ,为三期截流的决策和控制提供了有效的工具     

Enhanced thermal stability of a sputtered titanium-nitride film as a diffusion barrier for capacitor-bottom electrodes

The effect of a thin RuO_x layer formed on the Ru/TiN/doped poly-Si/Si stack structure was compared with that on the RuO_x/TiN/doped poly-Si/Si stack structure over the post-deposition annealing temperature ranges of 450–600°C. The Ru/TiN/poly-Si/Si contact system exhibited linear behavior at forward bias with a small increase in the total resistance up to 600°C. The RuO_x/TiN/poly-Si/Si contact system exhibited nonlinear characteristics under forward bias at 450°C, which is attributed to no formation of a thin RuO_x layer at the RuO_x surface and porous-amorphous microstructure. In the former case, the addition of oxygen at the surface layer of the Ru film by pre-annealing leads to the formation of a thin RuO_x layer and chemically strong Ru-O bonds. This results from the retardation of oxygen diffusion caused by the discontinuity of diffusion paths. In particular, the RuO_x layer in a nonstoichiometric state is changed to the RuO₂-crystalline phase in a stoichiometric state after post-deposition annealing; this phase can act as an oxygen-capture layer. Therefore, it appears that the electrical properties of the Ru/TiN/poly-Si/Si contact system are better than those of the RuO_x/TiN/poly-Si/Si contact system.     

MIM隧道发光结的负阻现象

本文介绍了薄膜隧道发光结的基本结构、发光机理，阐述了其Ｉ－Ｖ特性中的负阻现象。简单介绍了ＭＩＭ结构负阻的几种解释，根据热像仪照片和低温测试结果分析，再结合Ｄｅａｒｍａｌｅｙ导电模型，我们提出了ＭＩＭ负阻的物理模型，理论与实验符合较好，最后分析了负阻现象的应用前景。     

油气圈闭地质评价方法及应用

本从含油气系统理论出发，对圈闭成藏的油源，储层，圈闭，保存，配套史制定分级评价标准，并赋予相应的评价系数，在此基础上应用地质风险概率理论与模糊数学的方法，在微机上定量评价圈闭含油气性。     

双极关键工艺的在线统计分析

采用了双极晶体管作为双极工艺的测试结构,将在线工艺的统计分析理论应用于双极工艺,研制了双极工艺的统计分析软件。最后给出了双极工艺的某些分析结果。     

利用T2分布进行岩石孔隙结构研究

测井地层评价的基本任务除了要研究储层参数外，还要研究岩石孔隙结构。核磁共振测井技术和出现和应用，为测井解释研究孔隙结构提供了一种有效方法。通过研究泥质砂岩岩心核磁共振T2分布与压汞毛管压力曲线之间的关系，建立起二者之间的相互计算方法，从而为利用T2分布进行岩石孔隙结构研究提供了理论和方法的支持。