Electric-Field-Induced Triplet to Singlet Transition in Size-2 Trigonal Zigzag Graphene Nanoflake

Using Hartree-Fock Su-Sheriffer-Heeger (HF-SSH) model, we have studied the dependence of the energies of the ground (magnetic triplet state) and the first exited (nonmagnetic singlet state) states of the size-2 trigonal zigzag graphene nanoflake (size-2 NF) on the intensity of an external in plane static electric field at zero temperature. We identify a transition from the magnetic triplet state to a nonmagnetic singlet state in size-2 NF caused by the polarization energy induced by the in plane static electric field. This transition has a unique property of being accompanied by a sudden increase in the electric dipole moment of the size-2 NF.