钪凝固过程局域原子结构演化的第一性原理研究

Local Atomic Structure Evolution during Solidification of Scandium:An Ab Initio Study

采用第一性原理分子动力学模拟方法,研究了不同温度下钪熔体的局域原子结构演化和动力学行为。通过均方位移和速度自相关函数的分析,研究了钪熔体的原子动力学。当从高温降到接近熔点时,增强的背散射效应将直接影响钪熔体的动力学特性,如自扩散系数。进一步利用对关联函数、静态结构因子和键角分布分析了液态钪的局域原子结构。体系的第一配位间距随着温度降低而增大,有序度增加,扭曲二十面体结构增加。通过与其他常见金属比较,发现稀土金属钪在凝固过程的演化行为与其存在相似性的同时还保留独特的性质。本研究可以为从量子力学视角解释稀土金属熔体中的物理现象提供理论基础。

Ab initiomolecular dynamics simulation method was used to study the local atomic structure evolution and kinetic behavior of rare-earth metal scandium at different temperatures.The atomic dynamics of these melts were studied by analyzing the mean square displacements and velocity autocorrelation functions.When the scandium melt drops from high temperature to the melting point,the backscattering effect increases,which directly affects the dynamic characteristics of the system,such as the self-diffusion coefficient.Furthermore,the local atomic structure of liquid scandium was analyzed by using pair correlation function,static structure factor and bond angle distribution.It’s found that the first coordination spacing increases with the decrease of temperature,order of the system increases,and the number of twisted icosahedral structure also increases.Compared with other common metals,it is found that the evolution behavior of rare earth metal Sc during solidification is similar to that of other common metals,but it also retains its unique properties.This study can provide a theoretical basis for the interpretation of the physical phenomena in the melt of rare earth metals from the perspective of quantum mechanics.