Sternheimer shielding factors for atomic quadrupole moments: $\mathrm{np}(n+1\mathrm{})s$ configuration of C, Si, Ge, Sn, and Pb

Using Hartree-Fock-Slater wave functions and the Sternheimer perturbation-numerical method, values of atomic quadrupole shielding factor $R_{\ominus }$ are reported for the $\mathrm{np}(n+1\mathrm{})s$ excited-state configurations of C, Si, Ge, Sn, and Pb. The perturbation terms up to second order have been included. In all the cases a shielding effect greater than +1 has been obtained.