中文摘要：

利用分子动力学的方法研究了球形和立方体形Pd纳米微粒的晶格参数和结合能．研究表明，在一定的形状下，纳米微粒的晶格参数和结合能随着微粒尺寸的减小而降低；在一定尺寸时，球形纳米微粒的晶格参数和结合能要高于立方体形的纳米微粒的相应量．通过线形拟合分子动力学模拟的数据，定量的给出了形状效应对于纳米微粒晶格参数变化的贡献量约为总贡献量的7％，而形状效应对于结合能变化量的贡献为总变化量的25％．再次证明了具有自由表面的Pd纳米微粒的晶格发生收缩，模拟值与实验结果一致．

英文摘要：

The lattice parameters and cohesive energies of spherical and cubic Pd nanoparticles are studied by molecular dynamics method. It is shown that the lattice parameter and the cohesive energy decrease with decreasing the particle size for the specific particle shape. Both variation quantities of lattice parameter and cohesive energy for the spherical particles are higher than these for cubic ones. By fitting the simulation results, it is found that the shape effect can lead to 7% of total lattice parameter variation and 25% of total cohesive energy variation. The present results again confirmed that the lattice parameter of Pd nanoparticles with free surface contracted a little, which is consistent with the corresponding experimental results.