Calculation of hyperfine coupling constants of radicals by density-functional theory

Hyperfine coupling constants for small radicals have been calculated using the density-functional theory with a gradient-corrected (GC) local-spin-density approximation (LSDA). The agreement between the calculated and observed results is fairly good. The GC-LSDA is essential to calculate the isotropic hyperfine coupling constants for {π} radicals. For {σ} radicals, the simple LSDA also leads to relatively good results.