title: Conical intersections and diabatic potential energy surfaces for the three lowest electronic singlet states of H3 (+).
abstract: We calculate the adiabatic Potential Energy Surfaces (PESs) and the Non-Adiabatic Coupling Terms (NACTs) for the three lowest singlet states of H3 (+) in hyperspherical coordinates as functions of hyperangles (θ and ϕ) for a grid of fixed values of hyperradius (1.5 ⩽ ρ ⩽ 20 bohrs) using the MRCI level of methodology employing ab initio quantum chemistry package (MOLPRO). The NACT between the ground and the first excited state translates along the seams on the θ - ϕ space, i.e., there are six Conical Intersections (CIs) at each θ (60° ⩽ θ ⩽ 90°) within the domain, 0 ⩽ ϕ ⩽ 2π. While transforming the adiabatic PESs to the diabatic ones, such surfaces show up six crossings along those seams. Our beyond Born-Oppenheimer approach could incorporate the effect of NACTs accurately and construct single-valued, continuous, smooth, and symmetric diabatic PESs. Since the location of CIs and the spatial amplitudes of NACTs are most prominent around ρ = 10 bohrs, generally only those results are depicted.
authors.affiliation: Department of Physical Chemistry and Raman Center for Atom, Molecule and Optical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata - 700 032, India.
authors.forename: Saikat
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Department of Chemistry, University of Calcutta, Kolkata - 700 009, India.
authors.forename: Debasis
authors.initials: D
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Physical Chemistry and Raman Center for Atom, Molecule and Optical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata - 700 032, India.
authors.forename: Satrajit
authors.initials: S
authors.lastname: Adhikari