Direct calculation of transition matrix elements in relativistic coupled cluster theory

A procedure for calculating transition matrix elements of one-electron property operators in many-electron systems within the relativistic Fock space coupled cluster theory is implemented. The procedure implies constructing an effective property operator accurate up to the second order in cluster amplitudes and ensures connectivity of its diagrammatic representation and exact size-consistency. The results of pilot calculations of electronic transition dipole moments between low-lying states and excited-state radiative lifetimes for Sr and Ra atoms are presented.