钯的反演势的构建与研究

以面心立方金属钯为研究对象,基于第一性原理中的局域密度近似理论(LDA),计算了不同晶格长度下的原子间内聚能并得到其原子内聚能曲线.通过陈-莫比乌斯晶格反演势理论,得到了精确的反演对势曲线.采用不同势函数对该曲线拟合,通过对拟合效果的对比和分析,提出了全局精度较高的双指数型势函数.同时,分别采用第一性原理方法,原子嵌入势(EAM)方法和反演势数据计算了钯的声子谱.比较声子谱曲线发现,曲线的变化趋势是相似的,说明反演势可以合理的反应原子间相互作用.并且反演势方法所需的计算时间明显少于EAM势方法,说明反演势方法在计算量上有明显优势.最后,计算了金属钯的热膨胀系数,弹性模量和格林乃森常数等物理量.计算结果与实验数据基本符合,表明构建的钯的反演势是准确有效的.

Research and Foundation of Inversion Lattice Potential of Pd

The lattice cohesive energy curve of palladium was obtained through first-principles calculations based on local-density approximation theory(LDA). The accurate inversion potential curve was generated through Chen-M?bius inversion method. Based on the fitting results of different potential function, the double-exponential function to fit the inversion potential curve was presented. The phonon spectra of palladium were calculated through using the inversion potential data, the embedded atom method(EAM) potential theory and first principle method respectively to verify the reliability of the inversion potential. The tendency of these curves is consistent, which indicates that the inversion potential can reflect the interaction between atoms efficiently. Meanwhile, inversion potential method needs less time in the computation comparing with the EAM potential method, pointing out the inversion method has great advantage in the amount of calculation. In addition, thermal expansion coefficient, including elastic modulus and Grüneisen constant were calculated based on the fitting function and parameters. The results are in good agreement with experiment results, which implies that the inversion potential is accurate.