关注：

1） 结构搜索如何才能可靠

2）如何追踪声子虚频，获得稳定的结构

3）面心立方结构原子顶角和面心处的原子所处化学环境一样吗？

4）常见晶体结构分析

参考网址：

http://www2.uncp.edu/home/mcclurem/models/raytrace/fcc/fcc.html

Spacefilling Unit Cell
    A spacefilling unit cell only shows the portions of the atoms which lie inside the cell.

Each of the vertex atoms lie 1/8 inside the cell, and each face atom lies 1/2 inside the cell, giving the equivalent of four atoms inside the cell.

It should be apparent from this model that the atoms do not touch along an edge of the cell, but rather along the side diagonal, which connects opposite atoms along a face of the cell.