Non-adiabatic coupling and conical intersection(s) between potential energy surfaces for HeH₂⁺

Study of non‐adiabatic interactions among low‐lying electronic states of HeH2+ with its implication in its dissociation into various species

“…We have presented also the ADT‐angles and ADT‐matrix diagonals calculated with a three‐state HSS, comprising of 1 2 A′, 2 2 A′ and 3 2 A′; this shows no difference from the two‐state HSS calculations, which is a clear indication that a two‐state HSS is sufficient for this region of CS. Gupta etal 31 had a similar observation for the single (2,3) JT‐CI detected in their work.…”

“…These ions, atoms and photons are the reactants leading to simple diatoms as H 2 , H 2 + 3 and HeH +. 4,5 The chemical network involving all these neutral atoms, diatoms and corresponding ions have been a focus of experimental 6‐19 and theoretical 19‐31 studies for few decades. The pioneering work by McLaughlin and Thompson 21 was the first study of excited state of the HeH 2 + , which served as a source article for later works 23,27c to get a fit leading to analytical functional form of ground as well as excited‐state potential energy surfaces for HeH 2 + .…”

“…Gupta et al 31 have investigated the non‐adiabatic effect among three low‐lying electronic states of HeH 2 + in linear and C 2V geometry; they reported a single JT‐CI between the first and second excited electronic states for nearly linear geometry and another JT‐CI between the ground and first excited states of HeH 2 + in C 2V geometry. The study presented here, pursues a fully quantum mechanical treatment accounting non‐adiabatic interactions leading to the identification of a seam, in contrast to a single JT‐CI (as obtained by Gupta etal 31 ) between the first two excited states for a stretch of configuration space (CS), potential intersection between the third and fourth excited states at a CS within this stretch and investigates the effect of these interactions to the dissociation channels of HeH 2 + . The present communication also analyzes the possibility of a charge transfer process as a result of non‐adiabatic interaction between the first two excited states and its effect on dissociation yields.…”

“…Fazio etal 26 have presented a time‐dependent quantum mechanical study of dissociative charge transfer (DCT), He + + H 2 ( ν = 0, 1) → He + H + H + with all species in the ground electronic state. Gupta et al 31 have investigated the non‐adiabatic effect among three low‐lying electronic states of HeH 2 + in linear and C 2V geometry; they reported a single JT‐CI between the first and second excited electronic states for nearly linear geometry and another JT‐CI between the ground and first excited states of HeH 2 + in C 2V geometry. The study presented here, pursues a fully quantum mechanical treatment accounting non‐adiabatic interactions leading to the identification of a seam, in contrast to a single JT‐CI (as obtained by Gupta etal 31 ) between the first two excited states for a stretch of configuration space (CS), potential intersection between the third and fourth excited states at a CS within this stretch and investigates the effect of these interactions to the dissociation channels of HeH 2 + .…”

Beyond Born–Oppenheimer Constructed Diabatic Potential Energy Surfaces for HeH2+

“…Gupta et al investigated the nonadiabatic coupling between the ground and the first three excited states for the system and computed the adiabatic-to-diabatic transformation (ADT) angle to show the CIs between the ground and the first excited state in C 2 v geometries and between the first and the second excited state in collinear geometry. Mondal et al identified a seam of CIs between the first two excited states.…”