title: On the doublet states of the potassium trimer.
abstract: The potassium trimer is investigated in its lowest electronic doublet states, employing several high-level ab initio methods (coupled cluster with single, double, and noniterative triple excitations, multiconfiguration self-consistent field, and multireference Rayleigh-Schrodinger perturbation theory of second order). One-dimensional cuts through the lowest 12 electronic states at C(2v) symmetry give insight in the complex electronic structure of the trimer, showing several (pseudo-)Jahn-Teller distortions that involve two or three excited states. Contour plots of the involved molecular orbitals are shown to prove the validity of the shell model frequently used for a qualitative description of metallic clusters.
authors.affiliation: Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria. ahauser@sbox.tugraz.at
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Hauser
authors.forename: Carlo
authors.initials: C
authors.lastname: Callegari
authors.forename: Pavel
authors.initials: P
authors.lastname: Soldán
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Ernst