Universal Correlation of Electronic and Ionic Field Gradients in Noncubic Metals

From available quadrupole coupling constants in noncubic metals, measured with the sign, we have extracted in each case the component $e{q}^{\prime }$ commonly attributed to specific conduction-electron field gradients. These data reveal for the first time a systematic and universal dependence of $e{q}^{\prime }$ on the lattice gradient as well as the Sternheimer antishielding factor $1-{\gamma }_{\infty }$. This is unexpected from the point of view of current theoretical models of the electric field gradients in metals.