title: Reciprocity in the degeneracies of some tetra-atomic molecular ions.
abstract: Various ab initio computations, as, e.g., in G. J. Halász and Á. Vibók, Int. J. Quantum Chem. 111, 342 (2011), have shown that in molecules of the type (HCCH)(+), when the extremal H atoms are distorted from a linear form but maintain a planar geometry, a pair of conical intersections (ci) occur at such positions that the ratios of the distortional coordinates of the two atoms are in the two ci's reciprocals of each other. These computations have here been extended to locate the ci's also for HCNH. The two groups of results are explained by simple analytic perturbational expressions for the energy differences of the lowest adjacent electronic states, with inclusion of excited state effects.
authors: Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, Hungary. englman@vms.huji.ac.il
authors: Erika
authors: E
authors: Bene
authors: Tamás
authors: T
authors: Vértesi
authors: Robert
authors: R
authors: Englman