Many-body benchmarking of density functional theory local-registry energetics in bilayer InSe

Year: 2026

Type: article

Abstract: Density functional theory (DFT) is widely used to model twisted bilayers, but the accuracy of the local stacking energetics underlying such models remains uncertain. Here, we benchmark the local-registry landscape of bilayer InSe using diffusion quantum Monte Carlo (DMC). DFT predicts that AB, AAr, and ABr stackings, which share the same interfacial Se registry, are nearly degenerate within 1.5 meV/f.u. and exhibit nearly indistinguishable DFT charge-density responses. DMC instead separates these stackings by 8(5) and 41(4) meV/f.u., while the energy difference between the most stable and least stable registries reaches 60(7) meV/f.u.. These large energy separations show that the stacking energetics are not determined by the interfacial atomic motif alone but depend on the full registry and its associated many-body electronic response. More broadly, these results show that DFT-based moiré models can substantially underestimate local stacking-energy corrugation, with direct consequences for predicted structural relaxation, domain formation, and electronic reconstruction in twisted layered materials.

Source: Physical review. B./Physical review. B

DOI: 10.1103/1mnm-51c5

Authors: Jeonghwan Ahn, Abdulgani Annaberdiyev, Jovan Nelson, Nathaniel P. Stern, Hyeondeok Shin

Institutions: University of Illinois Urbana-Champaign, Sunchon National University, Oak Ridge National Laboratory, Northwestern University, Argonne National Laboratory

Language: English

Topic: 2D Materials and Applications

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, U.S. Department of Energy, UT-Battelle, Office of Science, Division of Materials Research, Basic Energy Sciences, Argonne National Laboratory

OpenAlex ID: W7221768685