Stacking Polymorphism of PtSe$_{2}$: Its Implication to Layer-dependent Metal-insulator Transitions

TL;DR

This study investigates the layer-dependent metal-insulator transition in PtSe$_{2}$, revealing the significance of stacking polymorphism and interlayer interactions in its electronic properties through advanced computational methods.

Contribution

The paper demonstrates the importance of stacking polymorphism and interlayer hybridization in PtSe$_{2}$, providing new insights into its phase stability and electronic behavior.

Findings

AA and AB-r stacking modes are nearly degenerate in energy.

Stacking polymorphism can lead to metallic electronic structures.

Interlayer hybridization significantly affects phase stability.

Abstract

Using diffusion Monte Carlo (DMC) and density functional theory (DFT) calculations, we examined the structural stability and interlayer binding properties of PtSe$_2$, a representative transition metal dichalcogenide (TMD) with strong interlayer interaction. Our DMC results for the bilayer revealed that AA and AB-r stacking modes are nearly degenerate, highlighting the significant role of interlayer hybridization in offsetting the energy cost due to larger interlayer separations in the AB-r mode. Additionally, our DMC-benchmarked DFT studies with the r$^2$SCAN+rVV10 functional demonstrated pronounced stacking polymorphism in few-layer PtSe$_2$, suggesting the potential for stacking faults and the formation of grain boundaries between different stacking domains which could develop metallic electronic structures. Thus this polymorphism, along with selenium vacancies, influences a layer-dependent metal-insulator transition observed in few-layer PtSe$_2$. Our findings emphasize the importance of both van der Waals interactions and interlayer hybridization in determining the phase stability and electronic properties of TMDs, advancing our understanding of their fundamental properties and refining theoretical models for practical applications in nanoelectronic devices.