An effective descriptor for predicting and designing high-temperature ambient-pressure superconductors

Searching for ambient-pressure conventional superconductors with critical temperatures (TC) higher than 40 K is a key challenge in the field of high-temperature superconductivity, mainly due to lack of efficient and effective models for rapidly screening candidate systems. In this work, we propose a simplified model that separates the dimensionless electron-phonon coupling (EPC) strength $$\lambda$$ into two components: while the EPC matrix elements evaluating the pairing strength are computationally expensive to obtain, the phonon-assisted nesting function $$P\left(\omega \right)$$, which evaluates the matching of electron bands and phonon spectra for forming potential electron pairs via phonons, can be easily and accurately calculated. Our model illuminates the critical role of $$P\left(\omega \right)$$ and its spectral integral $$P$$ in determining $$\lambda$$, i.e., high $$P$$ is a necessary condition leading to large $$\lambda$$ and thus high TC, which is further demonstrated by showing that the reported high-TC traditional superconductors in literatures all have high $$P$$. As an easily quantifiable parameter, $$P\left(\omega \right)$$ and $$P$$ provide an efficient and effective descriptor for accelerating the discovery and rational design of high-TC superconductors. By applying the model to screen over the Computational 2D Materials Database (C2DB), we successfully identify several high-TC superconducting systems as confirmed by accurate first-principles calculations. Our model opens new avenues for exploring high-TC systems.