Nuclear surface deformation and the anomalous Tc in high-pressure lithium: Extending the hole superconductivity framework

Within the framework of hole superconductivity, the non-monotonic dependence of the superconducting critical temperature TcTcTc of elemental lithium on pressure — specifically manifesting as a peak in the 30–45 GPa range followed by a decay at higher pressures — remains an unresolved anomaly. This letter reveals a rigid empirical correlation between the measured TcTcTc of high-pressure lithium and the nuclear quadrupole deformation parameter β2₂₂ of the ⁷Li nucleus under corresponding conditions of charge density anisotropy. Theoretical deduction indicates that the efficiency of hole carrier kinetic energy lowering, the core of Hirsch’s theory, is inevitably modulated by the geometric boundary conditions imposed by the nuclear surface shape. This physical constraint provides a complete, parameter-free explanation for the TcTcTc maximum and establishes a novel, falsifiable deep connection between low-energy nuclear structure and conventional superconductivity.