The non-relativistic expansion of Dirac-Coulomb energy and the non-retarded Breit interaction correction up to $\hat{I}{\pm }^8$order

Wanping Zhou, Sanjiang Yang, Haoxue Qiao

The relativistic corrections for the Dirac-Coulomb system are derived through the method of non-relativistic expansion. By expanding the large and small components of the Dirac wav…