Superconductivity in Potassium Doped P-Terphenyl

Aromatic hydrocarbon p-terphenyl (C₁₈H₁₄) has exhibited a diamagnetic signal when doped with potassium¹, which seems to indicate superconductivity with the critical temperature (T_c) up to 123 K. In order to explore the possible high T_c superconductivity in this material, we have performed the density functional theory calculations for the structural, electronic and phononic properties of the pristine and K₃ p-terphenyl. The crystal structure was optimized for the K₃ p-terphenyl and then the phonon spectra were calculated using the density functional perturbation theory. Contributions of phonon eigen-modes related to K-atoms and p-terphenyl inter and intra-molecular vibrations in the electron-phonon coupling and spectral function have been analyzed using EPW² in Quantum-Espresso suite. T_c was estimated from the Allen-Dynes formula with empirical values of Coulomb pseudopotential parameter. These results are presented in comparison with the structurally related and better studied K₃ picene³ (K₃C₂₂H₁₄) superconductor of T_c = 18 K. (References) 1. Ren-Shu Wang, Yun Gao, Zhong-Bing Huang, and Xiao-Jia Chen, arXive:1703.06641 (2017) 2. S. Poncé et al, Comput. Phys. Comm (2016). 3. M. Casuala, M.Clandra, G. Profeta and F. Mauri, PRL 107, 137006 (2011)