INTERACTION OF THE FE-GAS ATOMS( CATION WITH HEAVY NOBLE)

The diatomic iron-noble gas complexes FeAr+, FeKr+, FeXe+, and FeRn+ h ave been theoretically investigated by means of quantum-chemical calcu lations including an extensive treatment of electron correlation. Pote ntial energy curves and spectroscopic constants for the lowest (4) Del ta and (6) Delta states are derived from an open-shell coupled-cluster approach and the relative energies of all seven low-lying electronic states are evaluated by the multireference configuration interaction m ethod. While in FeAr+ the lowest quartet and sextet states are found t o be energetically almost degenerate, the heavier Fe+-noble gas molecu les are predicted to exhibit (4) Phi ground states. From a qualitative point of view bonding in these species is shown to be electrostatic i n origin with intrinsically higher interaction energies for the quarte t as compared to the sextet states. For calibration purposes, also an accurate calculation of the F-4(4s(0)3d(7))-D-6(4s(1)3d(6)) energy dif ference in the atomic Fe+ cation is provided. (C) 1995 American Instit ute of Physics.