Calculated spin-spin (SS) contribution to the ZFS parameter DI from the 1–4 center contributions defined in Table 2 for the truncated dinitroxyl as a function of the constrained central torsion, employing the EPR-II basis set. Results are given for DI (black filled upper triangles), 1-center-Coulomb- (+), 2-center-Coulomb- (
, black filled lower triangles), 2-center-Exchange- (grey filled lower triangles), 2-center-Hybrid- (open lower triangles), 3-center-Coulomb- (
, black filled circles), 3-center-Exchange- (open circles) and 4-center-integral contribution (x).