Zero-field splitting of compact trimethylenemethane analogue radicals with density functional theory

► Spin-spin Hamiltonian dominates the ZFS of stable TMM like di-radicals. ► DFT implementation of spin-spin interactions between the triplet state spin-centers. ► Validates the perception of negligible role of SOC in organic molecule. ► g-Tensor shift with restricted open-shell DFT-linear response technique.