THE IONIZATION-POTENTIALS OF F2 - A COMPARISON OF MULTICONFIGURATIONAL ELECTRON PROPAGATOR (MCEP) WITH OTHER LARGE-SCALE METHODS USING THE SAME BASIS SET

The multiconfigurational electron propagator technique (MCEP) gives reliable vertical ionization potentials (I.P.s) and electron affinities (E.A.s) for atoms and molecules, including open-shell and highly correlated systems. Shake-up and inner-valence I.P.s can be accurately obtained and characterized. In contrast, perturbative-type Green's function (PTGF) approaches are useful for closed-shell systems with relatively little correlation. Perturbative-type Green's functions cannot consistently reliably predict shake-up and inner-valence I.P.s. We have applied the MCEP method to F2 at 2.68 a.u. using 4s3p1d and 5s4p2d basis sets. In F 2, the complete active space of all valence orbitals is small. Hence, reliable MCEP results should be obtained for all valence ionization processes. In addition, comparison calculations are given using other large scale techniques, i.e., SCF, MCSCF, PTGF, and multireference CI using the same basis sets. The photoelectron spectrum of F2 below 30 eV is not well characterized experimentally except for the three lowest principal peaks, and apparently no reliable spectra have been reported for higher energies. We report and characterize several I.P.s in F2 0-60 eV, including several I.P.s that have not as yet been observed experimentally. 1985 American Institute of Physics.

THE IONIZATION-POTENTIALS OF F2 - A COMPARISON OF MULTICONFIGURATIONAL ELECTRON PROPAGATOR (MCEP) WITH OTHER LARGE-SCALE METHODS USING THE SAME BASIS SET Academic Article