论文标题
振动熵在SI中的关键作用（111）-7 $ \ times $ 7表面结构稳定性
Crucial role of vibrational entropy in the Si(111)-7$\times$7 surface structure stability
论文作者
论文摘要
我们研究了$ 3 \ times3 $，$ 5 \ times5 $，$ 7 \ times7 $，$ 9 \ times9 $和与Dimers-Adatoms-Adtacking Batters of Si $（111）$的表面表面介绍相关的无限大型结构的相对热力学稳定性。在考虑到表面自由能的振动贡献后，我们发现$ 5 \ times5 $结构比低温下的$ 7 \ times7 $更稳定。虽然预计在室温左右会发生相变，但$ 7 \ times7 \ rightArrow5 \ times5 $转换在冷却时的转换受到SI原子的有限迁移率的阻碍。结果不仅标志着振动熵在高温下的$ 7 \ times7 $结构形成中的关键作用，而且还指出了其在室温以下的亚稳态。
We investigate the relative thermodynamic stability of the $3\times3$, $5\times5$, $7\times7$, $9\times9$ and infinitely large structures related to the dimers-adatoms-stacking faults family of Si$(111)$ surface reconstructions by means of first-principles calculations. Upon accounting for the vibrational contribution to the surface free energy, we find that the $5\times5$ structure is more stable than the $7\times7$ at low temperatures. While a phase transition is anticipated to occur at around room temperature, the $7\times7\rightarrow5\times5$ transformation upon cooling is hindered by the limited mobility of Si atoms. The results not only flag a crucial role of vibrational entropy in the formation of the $7\times7$ structure at elevated temperatures, but also point for its metastable nature below room temperature.
