# Relativistic corrections to quantum mechanics of Coloumb potential

Systems of charged particles (such as atomic nuclei and electrons) can be described by nonrelativistic quantum mechanics with the Coloumb interaction potential. A fully relativistic description is given by quantum electrodynamics which is much more complex.

Is it possible to expand various quantities in QED as power series in 1/c i.e. around the nonrelativistic approximation? Examples of relevant quantities are:

• Ground state energy of a given set of charged particles
• Excited state energies
• Scattering cross sections of charged particles & their bound states (assuming we trace over the photons in the final state)
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Yes, it's possible. Look Breit equation, for example: en.wikipedia.org/wiki/Breit_equation – Vladimir Kalitvianski Dec 23 '11 at 12:45
Valdimir, as your comment is providing an answer, could you post it as an answer? – Piotr Migdal Dec 23 '11 at 15:17