The inclusion of HF exchange can reduce the self-interaction errors in DFT and lead to a better prediction of electronic structure. The improvement in accuracy of M06-2X (54% HF exchange) in predicting 2J compared to M06 (27% HF exchange) seems to suggest this. So to study the influence of HF exchange on the magnetic exchange coupling, the value of 2J was calculated for varying amounts of HF exchange in the B3LYP functional.