New method of allowing for the Coulomb interaction in the Logunov–Tavkhelidze quasipotential approach

The problem of taking into account Coulomb interactions of ladder type in the investigation of bound states in quantum electrodynamics by the quasipotential method is considered. The basic quasipotential equation and the expression for the quasipotential are written down in terms of two-time positive-frequency Coulomb Green's functions. A corresponding perturbation theory is developed, which makes it possible to calculate the shifts of the energy levels of hydrogen-like atoms to accuracy $\alpha^6 \ln\alpha$.