MnO的电子结构

采用杂化密度泛函方法对MnO的电子结构进行了研究.结果表明,杂化密度泛函方法明显改进了理论与实验的符合.MnO为电荷转移绝缘体,采用离子模型能较好地解释其电子结构.     

MnO的电子结构

采用杂化密度泛函方法对MnO的电子结构进行了研究。结果表明，杂化密度泛函方法明显改进了理论与实验的符合。MnO为电荷转移绝缘体，采用离子模型能较好地解释其电子结构。     

双成分负U模型的赝隙形成及其核弛豫行为

利用格林函数退耦合方法研究了双成分负Ｕ模型单粒子激发谱。为包含部分涨落效应在运动方程的第三步作退耦合近似。研究结果表明，在激发谱中存在赝隙。此外，计算得到的核自旋－晶格弛豫率与过掺杂的高温超导体的行为相符。     

尿素晶体的线性和非线性光学性质的从头算研究

采用从头计算平面波赝势方法（pwp）和局域密度近似,计算了尿素晶体的电子能带结构和光学性质,计算表明尿素晶体属直接带隙晶体,计算带隙为5,lleV。在剪切操作下,采用密度矩阵理论计算了介电常数和倍频系数,理论结果与实验符合甚佳,并成功地将二阶非线性光学系数谱的特征峰与介电函数光谱结合起来,按单、双光子共振项进行了分析。不同跃迁过程对二阶非线性光学系数的贡献的研究表明,二阶非线性光学极化率在低频下几乎全部来自于虚电子过程。     

赝二元合金FexMn1-xSi的磁相变和半金属磁体特性的第一性原理研究

用第一性原理研究了赝二元合金半金属磁体的电子结构和磁性质,定量地计算了态密度、离子的磁矩和能隙,定量计算的结果与实验基本一致。还给出了赝二元合金Fe_xMn_(1-x)Si从半导体到金属磁体相变的理论解释。更为重要的是:从具体的数值计算发现Fe0..5Mn0.5Si具有半金属磁体特性。     

二氯二硫脲合镉晶体的电子结构与光学性质的研究

采用基于平面波赝势方法（PWP）和局域密度近似（LDA）的第一性原理方法,研究了二氯二硫脲合镉（BTCC）晶体的电子结构,能态密度和线性光学性质。研究表明BTCC晶体属间接带隙晶体,带隙值为3.81 eV;电荷密度分析反映Cd和Cl原子,以及氢键对分子组合以及排列结构有重要影响。采用密度矩阵理论计算了介电常数和折射率,理论结果与实验符合甚佳。     

（ZnCd）Se／ZnSe多量子阱光电压特性

在温度１８￣３００Ｋ范围内测量了以ＧａＡｓ为衬底的Ｚｎ１－ｘＣｄｘＳｅ／ＺｎＳｅ应变层多量子阱的光电压谱。发现（ＺｎＣｄ）Ｓｅ／ＺｎＳｅ量子阱具有显著的量子限制效应；激子束缚能大，直至室温仍然能观测到清晰的激子跃迁峰。实验结果与理论计算结果基本一致。     

无网格对称粒子法中两类热边界条件的处理

第二、三类边界条件对无网格对称粒子法求解瞬态热传导问题的计算精度和稳定性有重要影响。提出一种有效的方法来处理这两类边界条件。该方法采用统一表达式描述两类边界条件,并将边界粒子分为光滑域内的边界粒子和非光滑域的边界粒子。对于前者,在温度导数的对称粒子近似中引入边界条件方程,精确地施加边界条件;对于后者,根据其相邻粒子的温度导数,采用具有一阶连续性的粒子近似,计算出其温度导数。应用该方法计算了一个数值算例。计算结果与解析解和有限元法的计算结果符合良好,且计算误差随时间呈下降趋势,说明该方法具有良好的精度和稳定性。     

SnO2(110)表面特性的密度泛函计算

根据密度泛函理论,采用广义密度近似和总体能量平面波赝势方法,计算了SnO2体结构,氧化（110）面,还原（110）面的结构及电子特性．计算结果发现,SnO2（110）表面结构发生了明显变形,还原（110）面驰豫情况类似氧化（110）面,氧空缺未对表面结构产生明显影响．氧化（110）面和还原（110）面电子态密度同体材料有较大不同,SnO2（110）的电导行为主要受氧空缺在禁带中引入的表面电子态的控制．     

铁基超导体SmOFeAs磁性的理论研究

为了从理论上研究新型5d过渡元素掺杂及压力诱导铁基超导体产生的超导电性,采用密度泛函理论自旋广义梯度近似方法(SGGA+U)计算分析了SmOFeAs的结构及Ir在Fe位上掺杂对体系电子结构和磁性质的影响.结果表明:铁基超导体SmOFeAs体系中Fe-3d电子的库仑势约为4 eV;物理外压和化学掺杂均可抑制SmOFeAs的反铁磁自旋密度波,使体系的磁有序度降低,与实验结果一致;Ir掺杂的SmOFe1-xIrxAs体系从反铁磁自旋密度波逐渐过渡为无磁性态,且超导态与反铁磁态共存并出现在磁性量子临界点附近.     

First Principle Calculation for the Electronic Bands and Absorption of CdTe_（1-x）Sb_x

The lattice parameters for the derivatives of cadmium telluride, CdTe1-xSbx, with the zinc blend crystal structure are calculated using the generalized gradient approximation method; which is based on the density functional theory (DFT). The effects of antimony (Sb) on the lattices, electric bands, electronic state density, absorption spectroscopy, and band gap between the valence band maximum (VBM) and the conduction band minimum (CBM) of CdTe1-xSbx are discussed. The results show that the antimonic atoms in the lattice are advantageous in promoting the hole concentration and conductivities of CdTe1-xSbx. The increase of the Sb content in CdTe1-xSbx reduces the interaction among Cd, Te, and Sb; resulting in a decreased binding energy within CdTe1-xSbx as well as an increase in the electronic gap. Also discussed are the mechanics for the lattice phase change of CdTe1-xSbx at x=0.5.     

ZnO薄膜的溶胶—凝胶法制备及其光学性质研究

采用溶胶—凝胶法分别在透明玻璃和Si衬底上制备出了ZnO薄膜。分别采用X射线衍射仪(XRD)、能量分散谱仪(EDS)、紫外可见分光光度计和荧光光谱仪对所制样品进行测试,研究了样品的结构特性、成分和光学特性。X射线衍射结果表明,所制备的ZnO薄膜为六角纤锌矿结构;ZnO薄膜的EDS能谱图表明薄膜包含O元素和Zn元素;透射光谱表明ZnO薄膜质量高,在可见光范围内具有较高的透射率,平均透射率在85%以上;吸收光谱表明在带隙处存在吸收边;从PL光谱观察到了显著的紫外发射峰。     

Nc-Si Thin Film Deposited at Low Temperature and Nc-Si Heterojunction Solar Cel

IntroductionMuchworkhasbeendonetostudythestruc-tureandpropertiesofthehydrogenatednano-crystallinesilicon(nc-Si∶H)thinfilmsinthepastfewyears[1～3].Ithasbeenreportedthatthesefilmshavemanygoodopticalandelectricalproper-ties[4～6].Severaldepositiontechniqueshavebeenestablishedtopreparenc-Si∶Hthinfilms,includ-ingplasmaenhancedchemicalvapordeposition(PECVD),hotwirechemicalvapordeposition(HWCVD)[7,8]andreactivemagnetronsputter-ing[9]withthesubstratetemperaturevaryingfrom150to250°C.Comparedwi…     

双辊连铸硅钢薄带硅含量对组织的影响

为对双辊连铸硅钢薄带的后续处理工艺提供理论依据和技术支持,用光镜、透射电镜和能谱分析等方法研究硅含量变化对薄带组织的影响.硅钢薄带的质量分数分别为0.5%,1.0%,3.0%,4.5%和6.5%.结果表明:硅含量对硅钢薄带组织的晶粒尺寸、晶界形貌和晶内位错等均有显著影响.当硅的质量分数为3.0%~4.5%时,薄带晶粒较大,晶界较纯净,晶内位错量和成分偏析较少.     

Effect of absorption layer on interior sound field of sonar dome

Using the finite element method (FEM) and boundary element method (BEM) and considering the sound absorption layer which is covered on the backing of the sonar dome, the interior field in the dome which is excited by the incident plane wave has been studied. This method is validated by comparing numerical results with that of classic elastic theory. Then the effect of parameters of the sound absorption layer on interior sound field has been analyzed. The numerical calculation results show that uniformity of interior sound pressure is improved when the backing is covered with a sound absorption layer. The thicker the layer is, or the higher the loss factor of layer is, the more uniform the sound field is.     

C15H13N2S2生物活性分子的光谱与热力学性质

为了获得N-苯亚甲基-4-[(2-氰基亚胺基-1,3噻唑烷-3-基)甲基]-噻唑-2-胺(C15H13N2S2)生物活性分子的光谱数据和不同温度下的热力学性质,使用密度泛函理论的B3LYP方法,进行几何构型优化和频率计算,使用含时密度泛函理论的DT-B3LYP方法,计算该分子在气相和不同溶剂中的电子吸收光谱.结果表明,优化得到的最稳定结构与实验晶体结构一致;气相中吸收峰出现在近紫外区370 nm处,溶剂几乎不影响跃迁性质,但吸收强度明显增大;标准摩尔熵与温度线性正相关,相关系数为0.999 05.     

Effect of oxygen content on structural and optical properties of single Cu2O film by reactive magnetron sputtering method

Cuprous oxide (Cu₂O) thin films have been deposited on glass substrate by reactive magnetron sputtering method using Cu target and argon oxygen gas atmosphere. Effect of oxygen flow rate on structural and optical properties of thin films has been discussed. The results of X-ray diffraction, ultraviolet-visible spectrophotometry and atomic force micrograph indicated that the condition window for single Cu₂O phase was about 3.8 to 4.4 cm³/min, and the optimum oxygen flow rate was 4.2 cm³/min. The optical band gap E _g of Cu₂O film was determined by using the data of transmittance versus wavelength, and slightly decreased from 2.46 to 2.40 eV with the increase of oxygen flow rate from 3.8 to 4.4 cm³/min. The Cu₂O film formed at the oxygen flow rate of 4.2 cm³/min had an optical band gap of 2.43 eV.     

诱导信息下的路径选择行为模型

本文为诱导信息下的驾驶员路径选择行为提出了一种基于决策场理论和贝叶斯理论的推理、预测、判断和路径选择决策的交互仿真模型. 首先,由贝叶斯推理理论建立诱导信息和以往出行经验共同作用下的路况动态更新模型;进而将其与基于决策场理论的动态路径选择模型相结合,构成诱导信息下的路径选择行为交互模型. 通过诱导信息下的路径选择行为动态模拟,获取诱导信息对路径选择行为的量化影响效能值. 仿真分析显示,诱导信息可信度、出行经验、路径固有偏好、决策速度/质量和路线选择标准是影响驾驶员对诱导信息做出响应的关键因素. 分析结果表明,决策场理论与贝叶斯理论相结合能较好地解释驾驶员路径选择行为的动态特性.     

Route Choice Behavior Model with Guidance Information

Using modeling and simulation methods, the driver's route choice behavior under guidance information is explored based on the combination of the decision field theory (DFT) and Bayesian theory. First, based on the Bayesian theory, a road condition dynamic updating model is presented in light of the guidance information and the driver's previous travel experiences. Then, the route choice behavior model under guidance information is formed by the fusion of the process-oriented vehicle dynamic route choice model and the road condition dynamic updating model. The developed model describes a driver's propensity to comply with received guidance information in terms of the interaction between perceived unreliability of the information, his previous travel experiences, preference for different road alternatives, decision-making speed/quality, and route selection criteria. The simulation results show that the combination of the DFT and Bayesian theory can effectively explain the driver's travel dynamics behavior.