SINGULARITY OF CR-ND ORBITAL (ANTI-)COLLAPSE

It is discovered and demonstrated for the first time that free ground Cr is singular in being the only 3d metal atom which develops dramatic orbital (anti-)collapse of its excited nd (3p --> nd, n greater-than- or-equal-to 3) orbitals. This finding is suspected to be a direct cons equence of the well known fundamental irregularity in the filling of t he 3d and 4s orbitals of the Cr ground-state configuration. It is also revealed that preliminary removing or excitation of the outermost 4s electron from the ground state of Cr conceals the orbital (anti-)colla pse of the subsequent nd excited orbitals. All the results obtained ar e the first evidences for rather a delicate balance of the intra-poten tial of Cr for the whole nd states. The calculations are performed in the frame of the 'spin-polarized' Hartree-Fock approximation.