Seams near seams: The Jahn-Teller effect in the E″1 state of N3+

Abstract

The (1)E(") electronic state of cyclic N(3) (+) arising from the singly excited electron configuration e('3)e(") is studied using multireference configuration interaction wave functions and a quadratic Jahn-Teller Hamiltonian determined from those calculations. It is shown that these two states have both a symmetry-required seam of conical intersections at D(3h) geometries and three proximal symmetry equivalent C(2v) seams, located on a circle with radius rho(0) from the D(3h) intersection. rho(0), a function of Q(s), the breathing mode, is quite small but only attains a value of zero at Q(s) (crit)=1.252 A, resulting in a confluence or intersection node of the three C(2v) seams with the D(3h) seam. At this point only, g= parallelg(Q(s)) parallel, the norm of half the energy difference gradient, the linear Jahn-Teller term, vanishes and the intersection is of the Renner-Teller type. The close proximity of the previously unreported C(2v) seams to the D(3h) seam over the range of Q(s) considered is a consequence of the small values of g, compared to the quadratic Jahn-Teller term. The present analysis has important implications in the study of Jahn-Teller effects in ring systems and provides insight into a recent report that characterized this D(3h) seam as a Renner-Teller or glancing intersection.