Theory of tunneling spectroscopy in a $Mn_{12}$ single-electron transistor by DFT methods

We present a theory of single-electron tunneling transport through a $Mn_{12}$ molecular magnet in the Coulomb blockade regime. We employ spin density functional theory to calculate the low-energy spin multiplet states for neutral and charged (anion and cation) $Mn_{12}$, split by spin-orbit interaction. Tunneling matrix elements between these states are the basic ingredients of a master equation formalism that gives the tunneling conductance as a function of the bias and gate voltage. We compare the results of this formalism with the ones obtained using a phenomenological giant-spin Hamiltonian and highlight the importance of the orbital degree of freedom included in our SDFT approach.