Perturbation theory within the O(4,2) group for a hydrogen-like atom in the field of distant charge

In the O(4,2) group an algebraic scheme of perturbation theory is proposed which enables one to find the energy and wavefunctions of bound states of a hydrogen-like atom in the field of the point charge placed at large distance R. It is shown that in each order of R-1 the correction to the wavefunction is expressed through a finite number of Coulomb functions of the discrete spectrum with a modified charge. Simple analytical expressions are obtained for the first and second corrections. (author)