Many-body benchmarking of DFT local-registry energetics in bilayer InSe
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.
Versions
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BibTeX
@misc{ahn2026manybody,
title = {{Many-body benchmarking of DFT local-registry energetics in bilayer InSe}},
author = {Jeonghwan Ahn and Abdulgani Annaberdiyev and Jovan Nelson and Nathaniel P. Stern and Hyeondeok Shin},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.01682},
eprint = {2607.01682},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.01682},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Many-body benchmarking of DFT local-registry energetics in bilayer InSe
AU - Jeonghwan Ahn
AU - Abdulgani Annaberdiyev
AU - Jovan Nelson
AU - Nathaniel P. Stern
AU - Hyeondeok Shin
PY - 2026
DA - 2026/07/02
PB - arXiv
DO - 10.48550/arxiv.2607.01682
UR - https://arxiv.org/abs/2607.01682
AB - 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.
ER -