Quadrupole interaction in the solid halogens—a new (not final) look

The nuclear quadrupole interaction in the molecular solids Cl2, Br2 and I2 is reanalyzed with the help of density functional calculations. Though the present formalism overestimates the intermolecular interaction responsible for the solid–gas frequency shift and the asymmetry parameter η, a consistent picture is derived by appropriate corrections. The published experimental values of η for Cl2 and Br2 are found to be in error.