SSRF前端区锯齿墙束流孔洞中子屏蔽的蒙特卡罗估算

主要关于上海同步辐射装置(SSRF)储存环电子引发产生的韧致辐射和中子辐射的研究.中子和光子经多种组合材料(厚度在5cm-115cm之间)屏蔽后的剂量特征由蒙特卡罗代码McNP和EGSnrc估算得到;蒙特卡罗计算表明,单一的材料如铅,铁和聚乙烯对高能中子是无效的生物屏蔽材料,而组合材料如铅或者铁加聚乙烯和铅或者铁加混凝土被认为是屏蔽高能中子很好的组合材料.铅铁等高Z材料加点包含有氢的低Z材料如聚乙烯是同时屏蔽高能中子和韧致辐射的一种比较好的组合材料选择.     

THEORETICAL STRENGTH AND PHASE STABILITY OF Cu AND Ni UNDER [100] UNIAXIAL LOADING

Based on Born's criteria we studied phase stability and theoretical strength of fcc crystals of copper and nickel under [100] uniaxial loading. The calculation was carried out using a simple and completely analytical embedded atom method(EAM) potential proposed by the present authors. For Cu, the calculated value of its theoretical strength (0.33×10¹¹ dyn·cm^-2) agrees well with the experimental value (0.30×10¹¹ dyn·cm^-2), while the calculated strain (9.76%) is somewhat larger than the experimental one (2.8%). For Ni, its theoretical strength and strain predicted using the EAM potential are found smaller than those predicted using a pair potential. It is worthy to note that unlike previous calculations, in which pair potentials were used and three unstressed fcc, bcc, and fct structures included (for Ni only fcc state is found stable, while for Cu both fcc and bcc states are predicted stable), in present calculations using EAM potential the [100] primary loading path passes through only two zeroes (a stable unstressed fcc structure and an unstable stress-free bcc structure) either for Cu or for Ni.     

MOLECULAR DYNAMICS STUDY OF LIQUID ALUMINIUM BY EMBEDDED-ATOM METHOD

A molecular-dynamics scheme in the embedded-atom method is shown to be the efficient and accurate in studying liquid aluminium system. The ability of the method in studying liquid system is demonstrated by calculating the intent heat, self-diffusion coefficient, pair distribution function of aluminium, and so on. All of the results agree well with experimental results. The background electron density is also calculated using this method, and the result shows that a discontinuous change occurs at melting point for the electron density in the system.     

DV-Xa计算a-SiO2电子结构

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壳聚糖-聚丙烯酰胺接枝共聚物接枝率的测定

根据溶液的折光指数增量与溶液的组成间存在定量关系的原理提出了一种测定接枝聚合物接枝率的新方法, 并用此方法测定了壳聚糖-聚丙烯酰胺接枝共聚物的接枝率. 结果通过元素分析法测定样品中氮元素的百分含量, 以及运用折光指数增量法测定已知比例的壳聚糖与聚丙烯酰胺(PAM)混合物中二者的质量百分比进行佐证. 结果表明, 折光指数增量法测定接枝共聚物的接枝率也是可行的.     

ICP-AES法在热镀锌合金分析中的应用

用ICP－AES法测定了热镀锌合金的AI、Cd、Cu、Fe、Pb、Sn等元素含量,考察了基体及无机酸浓度对被测元素分析线强度的影响,选择了仪器最佳工艺条件。试验结果表明,该法简便快速,检出限、精密度及准确度令人满意,能满足分析要求。     

嵌入原子势计算FCC金属的声子谱与表面驰豫

给出一个简单解析的嵌入原子势模型。该模型被用于计算ＦＣＣ金属的声子谱,表面驰豫,结构稳定性和总能曲线,计算结果与实验及更高水平的计算结果进行了比较。     

HX（X=F，C1，Br）酸性强度的理论计算

中用Gibbs自由能ΔGacid定义了HX(g)的酸性强度。研究表明，用MP2、QCISD和B3LYP三种量化方法计算所得的HX酸性强度与献值对比，其最大的相对误差仅为2．45％。其中，B3LYP方法的计算结果与献值最为接近，其误差在0．37—1．09％范围内。HF气态分子有明显的氢键作用，其二聚体分子酸性强度ΔGacid与单体分子的△Gacid值相比降低了约-5～-11％，此时氟化氢气体的酸性强度已不能单从HF单体分子的△Gacid值来衡量，而应考虑HF分子的氢键作用。     

LiH晶体在空气中腐蚀的理论研究

用CASTEP软件包中的GGA/RPBE基组,采用平面波超软赝势方法,计算了空气中主要成分H2O、O2、CO2、HCl、N2在LiH表面的最佳吸附方式,优化结构后的离解能、布居数和态密度.由吸附前后的态密度(DOS)图和电子转移数可知,H2O、O2发生的是化学吸附,CO2、HCl、N2发生的是物理吸附.