Relativistic configuration interaction method

Based on the projection operator method, the relativistic configuration interaction (RCI) method for many-body systems is presented. In this method, a variational one-body potential v(r) is introduced into a Hamiltonian and both a projection operator and a RCI wavefunction are constructed from the eigenfunctions for the one-body Hamiltonian involving v(r). This method is useful when one obtains variationally an optimum one-body projection operator used for constructing a relativistic many-body Hamiltonian without a disease of 'variational collapse'. Numerical applications of the method to helium-like atomic systems are carried out. (author)