  We present a theoretical approach for ab initio calculations of the one-loop
QED corrections to energy levels of heavy diatomic quasimolecules. This
approach is based on the partial-wave expansion of the molecular wave and Green
functions in the basis of monopole solutions, written in spherical coordinates.
By using so generated molecular functions we employed the existing
atomic-physics techniques to evaluate the self-energy and vacuum-polarization
corrections. In order to illustrate the application of our method, we perform
detailed calculations of the Dirac energy and QED corrections for the
1$\sigma_g$ ground state of homonuclear U$_2^{183+}$ as well as heteronuclear
U-Pb$^{173+}$ and Bi-Au$^{161+}$ quasimolecules.
