Finite nucleus effects, relativistic effects and picture change error in the IOTC/DKH2 contact spin densities of Cu, Ag, Au atoms

Sensitivity of contact spin density as well as electron density to the size of nucleus is investigated using the Gaussian model of nucleus and the point charge nucleus model. Scalar Infinite Order Two Component and scalar second order Douglas-Kroll-Hess quasirelativistic contact spin densities (spin densities at the nucleus) of Cu, Ag and Au atoms are considered. The non-relativistic contact spin densities and the valence s-orbital contact densities of Kramers restricted orbitals (Cu, Ag, Au atoms) are presented as well. The picture change error in the quasirelativistic calculations of spin densities is corrected by analytic means. Uncontracted triple-zeta UTZ+Ns basis sets are employed, where N is the number of additional tight s Gaussians. In addition, the impact of tight p and d Gaussians is briefly discussed.