Ground and excited states of iron-phthalocyanine: a DFT+DMFT analysis

Although the iron-phthalocyanine (FePc) molecule has been the subject of numerous experimental and theoretical studies, questions still remain about its ground and excited states. We have performed a Density Functional Theory+Dynamical Mean-Field Theory (DFT+DMFT) analysis of the spin resolved density of states of this interesting molecule to show that local dynamical effects (time-resolved on-site electron-electon interactions), which are inherently taken into account within DMFT, modify the DFT and DFT+U electronic spectrum of the molecule in the following way: they shift energy of a number of levels (most notably in the HOMO-LUMO energy range) and lead to new peaks. Such a modification may help resolve the issue of the ground state of FePc (complicated by the competing close-in-energy configurations) and can dramatically affect the transport, electronic and other propertiers of the molecule. Though further experimental test of the results are needed to quantify the accuracy of the DMFT approach for nanoscale systems, our results suggest that similar to extended systems time-resolved on-site electron-electron interactions play an important role in molecules that contain transition-metal atoms.