Density functional study of exchange coupling constants in single-molecule magnets:: The Fe8 complex

Theoretical methods based on density functional theory have been employed to analyze the exchange interactions in a Fe-8 complex with single-molecule magnet behavior. The four exchange coupling constants, calculated by using a hybrid functional, provide an accurate description of the experimental magnetic susceptibility and excitation energies. This complex has been also employed to check the accuracy of classical and quantum Monte Carlo methods to obtain macroscopic properties by comparison with the results obtained via exact diagonalization of the Hamiltonian matrix.