Improved relativistic self-consistent field convergence acceleration using direct inversion in the iterative subspace

Abstract

All-electron relativistic self-consistent field(RSCF) method has been improved by the convergence acceleration algorithm-direct inversion in the iterative subspace(DIIS) and was applied to several diatomic molecules. Changes in molecular properties due to relativistic effects ecome immense in $H_2$, LiF and BF as the value of c is artificcially decreased. The potential curves of rare gas dimers($He_2$, $Ne_2$, $Ar_2$) are investigated to check the difference of the relativistic ones from the nonrelativistic and it is found that repulsive forces in the nonrelativistic cases are overestimated. Open shell molecule NO is tested and its spin-orbit splitting $E_{so}$ is calculated as 141 $cm^{-1}$.