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.

Potential energy surface of the 12A′ Li2 + Li doublet ground state

“…This is also necessary for valence electron full configuration interaction (FCI) calculations where an ECP (a physically equivalent representation to the frozen core approximation which has no CV correlation) is substituted for the atomic electrons. This method has been used with great success for calculating both lithium dimer potential curves [25] and trimer potential surfaces of potassium [12].…”

“…To date, ab initio calculations for the sodium trimer have been done by several groups [8,9,10] as well as the potassium trimer [8,11,12]. In the case of lithium, the quartet ground state 1 4 A surface has been well studied [13,14,15,16] whereas the doublet system has been effectively ignored.…”

Homo- and heteronuclear alkali metal trimers formed on helium nanodroplets. Part II. Femtosecond spectroscopy and spectra assignments

“…Thus, by using femtosecond pump-probe spectroscopy, it was possible to measure vibrational frequencies of the previously unobserved dissociative B-state of the K 3 trimer, 41,45 which was later confirmed in ab initio calculations. 46 At high laser intensity, additional vibrational WP dynamics in the ground state was observed induced by resonant impulsive Raman scattering (RISRS). 40,44,45 The femtosecond dynamics of Na 3 in the B-state was found to be dominated by the symmetric stretch mode Q s in contrast to cw measurements.…”

A Jahn–Teller analysis of K3 and Rb3 in the electronic states 12E′ and 12E″

“…[20]. In a recently published article [21] we presented the first ab initio calculations on the doublet states of the potassium trimer, and provided an assignment of three experimental peaks in the range between 10,000 and 14,000 cm À1 (3 2 A 1 , 1 2 A 2 , 4 2 A 1 ) [12]. A peak near 12,400 cm À1 remained unassigned.…”