Fig. 10. The ab initio POLY_ANISO computed magnetisation blocking barrier for complexes (a) 1 {Cr₂Dy₂}, (b) 3 {Mn₂Dy₂}, (c) 5 {Fe₂Dy₂} and (d) 7 {Al₂Dy₂}. The x-axis indicates the magnetic moment of each state along main magnetic axis of Dy ions, while y-axis denotes the energy of the respective states. The thick black line indicates the Kramer's doublets as a function of computed magnetic moment. The indigo colour shows the possible pathway via Orbach/Raman relaxation. The dotted red lines represent the presence of QTM/TA-QTM between the connecting pairs. The numbers provided are the mean absolute value for the corresponding matrix element of transition magnetic moment. A thick cyan coloured arrow shows the zero field relaxation whereas a dotted cyan coloured arrow shows relaxation in an applied external field.