Scalar relativistic effects on energies of molecules containing atoms from hydrogen through argon

The study of scalar relativistic effects on molecules from the G3/99 test was presented using the stationary direct perturbation theory. The stationary direct perturbation theory was based on the expansion of the Dirac-Fock energy in inverse powers of the speed of light squared. It was observed that the relativistic energy reduces the atomization energies, electron affinities and ionization potentials. The trends in the energies were also observed with the changes in s orbital electron density and the density near the nucleus.