Nuclear quadrupole moment determination of35Cl,79Br,and127I

The electric-field gradient at the halide site is calculated in several compounds of Cl, Br, and I. The ab initio full-potential linear-augmented plane-wave method is employed with the generalized gradient approximation for exchange and correlation effects. The nuclear quadrupole moments of 3 5 Cl, 7 9 Br, and 1 2 7 1 are obtained by comparison of available experimental nuclear quadrupolar resonance data to the calculated electric-field gradients. The values of ‖Q( 3 5 Cl)‖=0.0855 b, ‖Q( 7 9 Br)‖ =0.330 b, and ‖Q( 1 2 7 I)‖=0.721 b are derived with ∼ 3% statistical uncertainty. These values are in agreement with recent values derived by other methods, and thus confirm the validity of the present methodology for the determination of electric-field gradients in solids.