Modeling Harmonic and Anharmonic Spin-Vibron Coupling in the Fe³⁺ Molecular Magnetic

The Fe³⁺ Molecular Magnetic Qubit has been predicted to be stable in two different spin states[1]. Since only one spin state has been clearly identified we have calculated infrared and Raman spectra for both magnetic states. Vibrational effects also influenced the magnetism through the spin-vibron effect which will be reported here. We have performed frozen phonon calculations on the chiral Fe₃O(NC₅H₅)₃(O₂CC₆H₅)₆ molecular cation and determined magnetic changes as a function of phonon displacement. We displace the Fe atoms from their equilibrium positions by, δ = 0, 0.01,-0.01,0.02,-0.02.. in atomic units, and allow all other atoms to relax. The resulting forces and energies are used to construct and solve a Hamiltonian that describes spin-spin, spin-orbit, and spin-vibron interactions. The forces as a function of displacement are further used to identify other interesting vibronic degrees of freedom. Progress on determining infrared frequencies that are most likely to lead to spin electric coupling will be reported.

[1] A. I. Johnson, F. Islam, C.M. Canali and M.R. Pederson, J. Chem. Phys. 151, 174105 (2019).