Prediction of Superconductivity in Potassium-Doped Benzene

To explore underline mechanism for the superconducting phase in recent discovered aromatic hydrocarbons, we carry out the first-principles calculations on benzene, the basic and the simplest unit of the series and examine the structural and phase stability when doped by potassium, K$_x$C$_6$H$_6$, $x=1,2,3$. We found that K$_2$C$_6$H$_6$ with the space group of $Pbca$ is the most stable phase with superconducting transition temperature T$_c$ around 6.2K. Moreover, we argue that all existing hydrocarbons should have superconducting phase in the same range, 5K $<$ T$_c$ $<$ 7K, when doped by potassium atoms.