Relativistic analogues of nonrelativistic integrals in R-matrix calculations

Relativistic analogues of integrals are applied to the nonrelativistic R-matrix code to demonstrate the possibilities of the method. An expression for the relativistic analogue of the multipole integral is obtained. Energy levels and electron impact excitation cross sections for transitions in C²⁺, Fe²²⁺ and W⁷⁰⁺, calculated with different codes, are compared. It is found that the relativistic analogues of integrals method shows good agreement with results calculated using a relativistic code.