Magnetic interactions in dehydrogenated Guanine–Cytosine base pair

Spin flip broken symmetry density functional theory is employed to determine the magnetic interactions in dehydrogenated Guanine–Cytosine (G–C) base pair. An antiferromagnetic (AFM) interaction between the electronic spins is suggested which gradually decreases at larger separation distances between the DNA bases. Beyond a certain separation distance, this AFM interaction becomes very weak and saturation in the values of magnetic coupling constant, J is observed. The variation in J values is in very good agreement with r−6 potential curve and also with the singlet–triplet energy gap. The overall investigation emphasizes the importance of H-bonding in determining the magnetic interactions in G–C diradicals.