Lowest 5Σ+ state of FeO: An ab initio investigation

Abstract

Hartree-Fock and limited configuration interaction calculations were used to investigate the 5Σ+ and related states of FeO with equilibrium separation of [inverted lazy s] 3.2 bohr. Very extended configuration interaction calculations were then performed to determine the properties of the lowest 5Σ+ state. This lowest state is determined to be close to the Hartree-Fock state investigated. The dissociation energy is estimated to be 2.00 ± 0.14 eV. It is concluded that the ground state of FeO is not 5Σ+.

Electronic Structure and Properties of FeOn and FeOn- Clusters

“…Table 1 provides a summary of the results of our calculations for FeO and FeO -. The ground state of FeO is found to be 5 ∆ (9σ 1 4π 2 δ 3 ), in agreement with experiment 19,20,66 and previous theoretical [23][24][25][26][27] calculations. As is seen from the table, our computed equilibrium bond length, harmonic frequency, and dipole moment are in good agreement with experiment.…”

“…The neutral iron oxides have received much more attention, especially iron monoxide, whose properties have been the subject of numerous experimental − and theoretical investigations. ,− For iron dioxide, infrared spectra were recorded by several groups − and the infrared spectra of FeO 3 and FeO 4 have been measured by Andrews et al Theoretical calculations on FeO n for n > 1 are scarce: some configurations of FeO 2 and FeO 3 were optimized using the generalized-gradient approximation for the exchange-correlation potential within the DFT theory . Calculations on the ground states of FeO 2 , FeO 3 , and FeO 4 and their isomers were performed at different levels (less accurate for FeO 3 and FeO 4 ) to help in the assignment of experimental infrared spectra .…”

Reactions of Laser-Ablated Iron Atoms with Oxygen Molecules in Condensing Argon. Infrared Spectra and Density Functional Calculations of Iron Oxide Product Molecules

“…Among iron oxides, the diatomic FeO molecule has been most thoroughly investigated. Its molecular constants have been obtained by matrix infrared, photoelectron, photoluminescence, microwave, and electronic spectroscopy, − and ab initio and semiempirical calculations have been done. − However, many disagreements are found in the literature for the triatomic FeO 2 molecule. Abramowitz, Acquista, and Levin reacted thermally evaporated iron atoms with oxygen during condensation with excess argon and assigned the 945.9 and 517.1 cm -1 bands to the ν 1 (O−O) and ν 2 (Fe−O) vibrations of the cyclic Fe(O 2 ) molecule; however, the 16/18 isotopic ratio for the first vibration is too low for this assignment.…”

Photoelectron spectroscopy of FeO− and FeO−2: Observation of low-spin excited states of FeO and determination of the electron affinity of FeO2

“…However, they have not been well understood and spectroscopic data on these simple molecules are scarce, in particular, for FeO 2 , whose ground state structure and symmetry is not yet known. Several spectroscopic [1][2][3][4][5][6][7][8] and theoretical 9,10 studies have focused on FeO, and its ground state has been established to be 5…”

“…However, theoretical calculations have predicted many more low-lying excited states that have not been observed experimentally. 9,10 To our knowledge, there has been no PES study on FeO 2…”