Effects of the choice of the exchange-correlation functional on high-temperature superconductivity predictions in covalent-cage M(BN)5 family
Abstract
The recent experimental synthesis of covalent cage superconductors has ignited hopes for ambient-pressure high-temperature superconductivity, while the computational strategy for discovering new materials poses challenges for accurately estimating superconducting properties. Here, we quantified the response of electron-phonon coupling (EPC) properties in M(BN)5 superconductors to different exchange-correlation (XC) effects using high-throughput first-principles calculations. We found that the metallic covalent bonds responsible for superconductivity exhibit anomalously high sensitivity to functional selection uncertainty, distinguishing them from conventional superconductors mediated by metallic bonding. The widely used PBE functional systematically overestimates lattice volumes, inducing phonon softening, enhanced EPC, and consequent Peierls instability. In contrast, PBEsol, which is more accurate through enhanced treatment of short-range interactions, eliminates imaginary frequencies in Rb(BN)5 that appear at the PBE level, yielding an outstanding superconducting critical temperature (Tc) of 113 K at ambient pressure and 138 K at 2 GPa. Enhanced electron localization and short-range correlation in covalent bonds manifest through dual mechanisms: phonon hardening at the lattice scale and band widening at the electronic scale, which collectively suppress Peierls distortion and delocalize antibonding states. Pressure-dependent analysis reveals that compression attenuates phonon discrepancies between XC functionals, whereas electronic properties remain notably sensitive to XC-induced perturbations of fine electronic bands near the Fermi level.
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BibTeX
@misc{wan2026effects,
title = {{Effects of the choice of the exchange-correlation functional on high-temperature superconductivity predictions in covalent-cage M(BN)5 family}},
author = {Zhongyu Wan and Guo-Hua Zhong and Cheng-wei Ju and Ruiqin Zhang and Hai-Qing Lin},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18171},
eprint = {2610.18171},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18171},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Effects of the choice of the exchange-correlation functional on high-temperature superconductivity predictions in covalent-cage M(BN)5 family
AU - Zhongyu Wan
AU - Guo-Hua Zhong
AU - Cheng-wei Ju
AU - Ruiqin Zhang
AU - Hai-Qing Lin
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18171
UR - https://arxiv.org/abs/2610.18171
AB - The recent experimental synthesis of covalent cage superconductors has ignited hopes for ambient-pressure high-temperature superconductivity, while the computational strategy for discovering new materials poses challenges for accurately estimating superconducting properties. Here, we quantified the response of electron-phonon coupling (EPC) properties in M(BN)5 superconductors to different exchange-correlation (XC) effects using high-throughput first-principles calculations. We found that the metallic covalent bonds responsible for superconductivity exhibit anomalously high sensitivity to functional selection uncertainty, distinguishing them from conventional superconductors mediated by metallic bonding. The widely used PBE functional systematically overestimates lattice volumes, inducing phonon softening, enhanced EPC, and consequent Peierls instability. In contrast, PBEsol, which is more accurate through enhanced treatment of short-range interactions, eliminates imaginary frequencies in Rb(BN)5 that appear at the PBE level, yielding an outstanding superconducting critical temperature (Tc) of 113 K at ambient pressure and 138 K at 2 GPa. Enhanced electron localization and short-range correlation in covalent bonds manifest through dual mechanisms: phonon hardening at the lattice scale and band widening at the electronic scale, which collectively suppress Peierls distortion and delocalize antibonding states. Pressure-dependent analysis reveals that compression attenuates phonon discrepancies between XC functionals, whereas electronic properties remain notably sensitive to XC-induced perturbations of fine electronic bands near the Fermi level.
ER -