The Role of Stacking Pattern in the Electronic Properties of PdX ₂ (X = S, Se, Te) Bilayers via DFT for Applications in Twistronics

High Resolution Image Download MS PowerPoint Slide Layered chalcogenides allow control of the interlayer stacking registry, which governs stability and electronic properties; however, an atomistic understanding of stacking descriptors remains limited. Using PdX 2 (X = S, Se, Te) bilayers as a model, we perform van der Waals-corrected density functional calculations (PBE+D3) and hybrid HSE06 calculations for registries generated via lateral translation. While bulk-like registries remain the thermodynamic ground states, metastable configurations exhibit longer interlayer distances and weaker binding. Fundamentally, the stacking-dependent electronic response follows a simple sequence: variations in registry and interlayer distance modulate the overlap of facing chalcogen X p z orbitals. This change affects Pauli repulsion and drives spatial rehybridization with intralayer Pd d and surface X p states, which set the layer polarization. For PdS 2, tightly bound S 3 p states suppress this response, enforcing a rigid-charge regime where stacking controls interlayer separation and in-plane optical anisotropy while preserving a semiconducting phase. In contrast, extended Se 4 p orbitals yield a competitive regime where stacking-induced rehybridization drives pronounced interfacial charge asymmetry, leading to stacking-driven phase switching across semiconducting, semimetallic, and metallic states. In metallic PdTe 2, spatially diffuse Te 5 p orbitals increase structural sensitivity, yielding an inverted charge-transfer regime and an anomalous surface dipole. These distinct hybridization regimes govern surface electrostatics: the work function decreases from PdS 2 to PdTe 2, tuned by steric separation in the sulfide limit versus enhanced stacking-induced charge asymmetries in the selenide and telluride systems, yielding modulations up to 17% in PdSe 2 . Ultimately, lateral stacking provides a practical control parameter to engineer interfacial electrostatics and phase transitions in PdX 2 bilayers, which are directly relevant to twistronic device concepts.