arXiv 1503.061232015-03-20cond-mat.mtrl-sci

锆薄膜热膨胀特性的分子动力学模拟研究

Study of peculiarities of the thermal expansion of zirconium thin films by molecular-dynamics simulation

E. B. Dolgusheva, V. Yu. Trubitsin

备注：: 7 pages, 8 figures

摘要：

采用分子动力学（MD）方法，在嵌入原子模型中得到了多体原子间相互作用势，研究了（100）和（110）晶向的$bcc$和$fcc$锆薄膜在恒零压下的热膨胀特性.结果表明，弛豫后立方晶格变为四方晶格（$bct$和$fct$），亚稳态$fct$薄膜的热膨胀线性系数在很宽的温度范围内为负值.计算了$bct$和$fct$ Zr薄膜表面和内层沿$x,y,z$轴极化的总振动态密度和局域振动态密度随温度的变化关系。结果表明，薄膜晶格参数随温度变化的各向异性是表面原子层振动态密度行为的特殊性的体现。随着温度的升高，晶格参数的减少观察到的方向上发生软化的本地振动模式。

英文摘要：

The peculiarities of thermal expansion of $bcc$ and $fcc$ zirconium films with (100) and (110) crystallographic orientations are studied at a constant zero pressure by the molecular dynamics (MD) method with a many-body interatomic interaction potential obtained in the embedded atom model. It is shown that after relaxation the cubic lattices become tetragonal ($bct$ and $fct$), and for the metastable $fct$ films the linear coefficients of thermal expansion in the film plane have a negative value in a wide temperature range. The total and local vibrational density of states (VDOS) polarized along the $x,y,z$ axes is calculated for the surface and interior layers of $bct$ and $fct$ Zr films as a function of the temperature. It is shown that the peculiarities of the behavior of the vibrational density of states of surface atomic layers manifest themselves in the anisotropy of the changes of the film lattice parameters with temperature variation. A decrease in the lattice parameters with increasing temperature is observed in the directions where there occurs a softening of the local vibrational modes.

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摘要：

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