Correction to the Josephson current in the second order of perturbation theory in the transparency

A calculation is made of the correction in second order in the transpareney to the Josephson current flowing through a tunnel contact that joins two identical superconductors. The dependenee of this correction on the coherent difference of the phases $\varphi$ between the superconduetors is represented as a linear combination of $\sin\varphi$ and $\sin2\varphi$.