Electrons distribution competition: A negative correlation between relative potential energy and bandgap in hexagonal boron nitride

Revealing the microscopic origins of macroscopic properties and the correlations among them are of value to performance improvement and reasonable structure design of materials. Recently, the interlayer interactions and bandgap adjustment of two-dimensional materials have been attributed to electron redistribution (mainly charge transfer). However, it remains unclear how the distribution of electrons determines the change in interlayer interaction and bandgap simultaneously. Here, based on the first-principles calculations, we present an interesting physical phenomenon: there is a surprising negative correlation between relative potential energy (i.e., sliding energy barrier) and bandgap in hexagonal boron nitride (h-BN) bilayers. More notably, relative potential energy and bandgap will reverse at the same sliding position and normal pressure. The analysis of electronic structure indicate that the reversion of the potential energy fluctuation is induced by the reversal of the distribution of interlayer charge density, yet the change in bandgap is caused by the reversal of the contribution of B atomic electrons (p orbital) to the intralayer B-N bond. And ultimately, we concluded that the negative relationship between the potential energy and bandgap is the reflection of competitive relationship of electrons distribution between interlayer and intralayer.