First-principles calculations for electronic, optical and thermodynamic properties of ZnS

The electronic, optical and thermodynamic properties of ZnS in the zinc-blende （ZB） and wurtzite （WZ） structures are investigated by using the plane-wave pseudopotential density functional theory （DFT）. The results obtained are consistent with other theoretical results and the available experimental data. When the pressures are above 20.5 and 27 GPa, the ZB-ZnS and the WZ-ZnS are converted into indirect gap semiconductors, respectively. The critical point structure of the frequency-dependent complex dielectric function is investigated and analysed to identify the optical transitions. Moreover, the values of heat capacity Cv and Debye temperature θ at different pressures and different temperatures are also obtained successfully.     

Elastic and thermodynamic properties of c-BN from first-principles calculations

The elastic constants and thermodynamic properties of c-BN are calculated using the first-principles plane wave method with the relativistic analytic pseudopotential of the Hartwigen, Goedecker and Hutter (HGH) type in the frame of local density approximation and using the quasi-harmonic Debye model, separately. Moreover, the dependences of the normalized volume V/V₀ on pressure P, as well as the bulk modulus B, the thermal expansion α, and the heat capacity C_V on pressure P and temperature T are also successfully obtained.     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

MgB2状态方程的第一原理计算

利用基于局域密度近似框架下的第一原理平面波方法, 结合HGH型相对论分析赝势, 对MgB2的晶格参数和状态方程进行了计算,所得结果与实验值及其他理论得到的计算值相符合.     

高效液相色谱-串联质谱法测定食品包装材料中全氟辛烷磺酰基化合物(PFOS)

建立了用高效液相色谱-串联质谱(HPLC/MS/MS)结合快速溶剂萃取测定食品包装材料中全氟辛烷磺酰基化合物(PFOS)的方法。采用乙腈溶剂,快速溶剂提取食品包装材料中的PFOS,提取液经0.2μm有机滤膜过滤后,以V(乙腈)∶V(10 mmol/L乙酸铵溶液)=80∶20为流动相,经HPLC分离后用多级反应监测(MRM)方式测定。用两个子离子的相对丰度定性,外标法定量。PFOS在0.002~0.1μg/mL范围内线性良好(R2=0.998),回收率为93.8%~101%,精密度RSD为1.6%~3.1%,方法检出限为0.4μg/m2(S/N≥10),满足欧盟法规对食品包装材料中PFOS的限量检测要求。方法可用于食品包装材料中PFOS的检测。     

GaAs纳米结点电子输运性质的第一性原理计算

运用密度泛函理论结合非平衡格林函数的方法,对GaAs团簇与两半无限Au(100)-3×3电极以顶位对顶位、顶位对空位、空位对顶位、空位对空位四种不同耦合形貌构成的Au-GaAs-Au纳米结点电子输运性质进行了理论计算.对结点在不同距离下的结构进行了几何优化,模拟了结点拉伸直至断裂的过程.计算结果得到四种构型结点在两极距离分别为1.389 nm,1.145 nm,1.145 nm,0.861 nm时,结构最稳定.对于各稳定结构,Ga-As键长分别为0.222 nm,0.235 nm,0.227 nm,0.235 nm,其平衡电导分别为2.33 G0,1.20 G0,1.90 G0,1.69 G0,结点具有很好的电子输运性质.在-1.2—1.2 V的电压范围内,所有结点的电流-电压都表现出近线性关系.     

Au-MgB2-Au纳米结点的负微分电阻效应

运用密度泛函理论结合非平衡格林函数的方法对MgB₂直线原子链与两半无限Au(100)电极构成纳米结点的电子输运特性进行了第一性原理计算．在模拟Au-MgB₂-Au纳米结点的拉伸过程中,计算了结点在不同距离下的结合能与电导．结果发现结点的Au?B键长为1.90 ?,B-Mg键长为2.22 ?时,结合能最大,结构最稳定,此时结点平衡电导为0.51G₀ (G₀=2e²/h)．通过计算投影态密度发现电子通     

“厚基础、宽口径、分层次、求创新、拔尖型”人才培养方案的研究

针对传统大学物理实验教学体系存在的问题,重建大学物理实验教学体系。构建"厚基础、宽口径、分层次、求创新、拔尖型"的人才培养方案。建立自主、合作、研究式的教学模式,激发学生的学习兴趣,培养学生的创新与动手能力。     

Structural and thermodynamic properties of OsN2 from first-principles calculations

We investigate the structural and thermodynamic properties of OsN2 by a plane-wave pseudopotential density functional theory method. The obtained lattice constant,bulk modulus and cell volume per unit formula are consistent with the available theoretical data. Moreover,the pressure-induced phase transition of OsN2 from pyrite structure to fluorite structure has been obtained. It is found that the transition pressure of OsN2 at zero temperature is 67.2 GPa. The bulk modulus B as well as other thermodynamic quantities of fluorite OsN2 (including the Gru¨neisen constant γ and thermal expansion α) on temperatures and pressures have also been obtained.     

Time-Dependent Local Density Approximation Calculations for Absorption Spectra of Small Carbon Clusters

Absorption spectra for Cn clusters (n = 2-8) are calculated using an adiabatic time-dependent density functional formalism within the local density approximation (TDLDA). We compare the calculated spectra with those computed using a simple local density approximation approach. It is readily observed that the TDLDA spectra display a significant blue shift with respect to the Kohn-Sham eigenvalue spectra. The calculated spectra exhibit a variety of features that can be used for comparison against future experimental investigations. We also obtain a significant threshold absorption, which can distinguish different ground states of the carbon clusters.