VB electronic structure of iron phthalocyanine an experimental and theoretical photoelectron spectroscopy study

A Variable Energy Photon Electron Spectroscopic study of FePc has been perfomed and compared with state-of-art DFT calculations.
B. Brena et al. J. Chem. Phys. (2011)


The electronic structure of iron phthalocyanine (FePc) in the valence region was examined within
a joint theoretical–experimental collaboration. Particular emphasis was placed on the determination
of the energy position of the Fe 3d levels in proximity of the highest occupied molecular orbital
(HOMO). Photoelectron spectroscopy (PES) measurements were performed on FePc in gas
phase at several photon energies in the interval between 21 and 150 eV. Significant variations of
the relative intensities were observed, indicating a different elemental and atomic orbital composition
of the highest lying spectral features. The electronic structure of a single FePc molecule was
first computed by quantum chemical calculations by means of density functional theory (DFT). The
hybrid Becke 3-parameter, Lee, Yang and Parr (B3LYP) functional and the semilocal 1996 functional
of Perdew, Burke and Ernzerhof (PBE) of the generalized gradient approximation (GGA-)type,
exchange-correlation functionals were used.

The DFT/B3LYP calculations find that the HOMO is a
doubly occupied π-type orbital formed by the carbon 2p electrons, and the HOMO-1 is a mixing of
carbon 2p and iron 3d electrons. In contrast, the DFT/PBE calculations find an iron 3d contribution
in the HOMO. The experimental photoelectron spectra of the valence band taken at different energies
were simulated by means of the Gelius model, taking into account the atomic subshell photoionization
cross sections. Moreover, calculations of the electronic structure of FePc using the GGA+U
method were performed, where the strong correlations of the Fe 3d electronic states were incorporated
through the Hubbard model. Through a comparison with our quantum chemical calculations
we find that the best agreement with the experimental results is obtained for a Ueff value of 5 eV.

Retrive article

Valence-band electronic structure of iron phthalocyanine: An experimental and theoretical photoelectron spectroscopy study
Barbara Brena, Carla Puglia, Monica de Simone, Marcello Coreno,
Kartick Tarafder, Vitaly Feyer, Rudra Banerjee, Emmanuelle Göthelid,
Biplab Sanyal, Peter M. Oppeneer, and Olle Eriksson
J. Chem. Phys. 134 (2011) 074312; doi:10.1063/1.3554212

 

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