氯化钠型结构有限晶格振动

编制了氯化钠型结构各种晶体的晶格振动通用程序;它适用于循环或自由边界条件。令体系原子总数由少至多地分别计算得到了趋向于宏观尺寸极限的零维、一维、二维和三维体系的结果。体系的键角和键长力系数之比增大时,晶化模软化使结构不稳定,导致其升华或熔解。比较了两种边界条件所得到的完全不同的结果。在自由边界条件下简谐模频谱分布随结构中重和轻原子重比增大而分裂成三支;低频、中频和高频之间共出现两个禁区。低频支主要是重原子的振动;高频支重原子大致不动;中频支两种原子都振动。

Finite Lattice Vibration for Crystal with NaCl Structure Type

The common program, which can calculate the lattice vibration for various crystals with NaCl structure type, has been made and it is applicable to cyclic or free boundary condition. Let the amount of atoms in a system become more and more, the computation from zero dimension to three dimensions which tend to the limit of macroscopic sizes have been got. With the ratio of bond angle force constant and bond length one increasing, the crystallized mode softens and makes the structure unstable, finally led to sublimation or melting of the crystal. The different results of lattice vibration in above boundary conditions have been compared. In free boundary condition, when the ratio of masses of heavy and light atoms in the structure increases, there are three branches in the harmonon mode spectrum, in which appear two forbidden gaps. It's primarily the heavy atoms to vibrate in the branch of low frequency, while they hardly vibrate in the part of high frequency. In the branch of middle frequency, both types of atoms vibrate.