Basis sets Fock operator technique

Based on the Dirac-Coulomb-Breit operator, most known methods of quantum-chemical ab initio electronic structure determination have been implemented by now also for four-component spinors. This comprises time-honoured pioneering work on atoms in the Dirac-Hartree-Fock framework, using numerical techniques and basis set expansion techniques, " as well as work for molecules in Dirac-Har tree-Fock approximations with global basis sets " or finite elements and elaborate techniques to treat relativity and correlation on the same footing. " ... 

---