We study the inter-layer coupling in bulk tin selenide (SnSe) through density functional theory based calculations. Different approximations for the exchange-correlation functionals and the van der Waals interaction are employed. By performing comparison with graphite, MoS₂ and black phosphorus, we analyze the inter-layer coupling from different points of view, including the binding energy, the low frequency inter-layer optical phonons, and the inter-layer charge transfer. We find that, there is a strong charge transfer between layers of SnSe, resulting in the strongest inter-layer coupling. Moreover, the charge transfer renders the inter-layer coupling in SnSe not of van der Waals type. Mechanical exfoliation has been used to fabricate mono- or few-layer graphene, MoS₂ and black phosphorus. But, our results show that it may be difficult to apply similar technique to SnSe.

我们通过基于密度泛函理论的计算研究了块状硒化锡（SnSe）的层间耦合。对于交换相关函数和范德华相互作用，采用了不同的近似值。通过与石墨，MoS ₂和黑磷的比较，我们从不同角度分析了层间耦合，包括结合能，低频层间光子和层间电荷转移。我们发现，SnSe层之间存在很强的电荷转移，从而导致最强的层间耦合。而且，电荷转移使得SnSe中的层间耦合不是范德华式的。机械剥离已用于制造单层或多层石墨烯MoS ₂和黑磷。但是，我们的结果表明，将类似技术应用于SnSe可能很困难。