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Superconductivity in RbH$_{12}$ at low pressures: an \emph{ab initio} study
by Đorđe Dangić, Yue-Wen Fang, Ion Errea
Submission summary
| Authors (as registered SciPost users): | Dorde Dangic |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202507_00044v2 (pdf) |
| Date submitted: | Jan. 16, 2026, 12:01 p.m. |
| Submitted by: | Dorde Dangic |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
High-pressure polyhydrides are leading contenders for room temperature superconductivity. The next frontier lies in stabilizing them at ambient pressure, which would allow their practical applications. In this first-principles computational study, we investigate the potential for record-low pressure stabilization of binary superhydrides within the RbH$_{12}$ system, including lattice quantum anharmonic effects in the calculations. We identify five competing phases for the pressure range between 0 and 100 GPa. Incorporating anharmonic and quantum effects on ion dynamics, we find the $Immm$ and $P6_3/mmc$ phases to be the most probable, potentially metastable even at pressures as low as 10 GPa. Notably, all phases exhibit metallic properties, with critical temperatures between 50 and 100 K, within the pressure range where they are dynamically stable. These findings have the potential to inspire future experimental exploration of high-temperature superconductivity at low pressures in Rb-H binary compounds.
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- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
List of changes
- The sentence in the last paragraph of the introduction has been revised following the first referee's suggestion.
- A reference to the first-principles Coulomb-interaction calculation has been added in the Methods section.
- The first paragraph on pg.~3 now explicitly states that at $0$~K the Gibbs free energy equals the enthalpy.
- The second-to-last paragraph on pg.~3 now clarifies that the values shown in Fig.~1 are relative enthalpies and not distances from the convex hull.
- The first paragraph on pg.~5 has been updated to clarify that the negative phonon frequencies in Fig.~3 arise from interpolation artifacts.
- Additional information regarding the ab-initio treatment of Coulomb repulsion in the Migdal--Eliashberg calculations has been included in the second paragraph on pg.~6.
- Figure~5 now presents the electronic density of states calculated using the same Gaussian smearing employed in the electron-phonon calculations.
- The caption of Fig.~6 has been revised to better explain how the superconducting critical temperatures were obtained.
- All Migdal--Eliashberg calculations involving $\mu^*$ have been repeated using $\mu^* = 0.118$, consistent with the value obtained for the $Immm$ phase.
- A section describing additional calculations using larger SSCHA supercells has been added to the Supplementary Material.
- A section explaining our approach to solving the Migdal--Eliashberg equations with an ab-initio Coulomb interaction has been added to the Supplementary Material.
- Nine additional references have been included to cite the relevant work that enabled the additional calculations.