In 2006, Abe et al. extended the CASPT2 method for the spin-dependent relativistic framework, building upon the diagonal approximation originally reported by Anderson et al. In the present study, we modified the relativistic CASPT2 program developed by Abe et al. to incorporate the RASCI-RASPT2 program and enable MPI parallel calculations, utilizing the DIRAC software. In the subsequent paragraphs, we provide a brief overview of the theoretical aspects of relativistic CASPT2 and RASPT2 methods.