Conical intersections and diabatic potential energy surfaces for the three lowest electronic singlet states of H-3(+)

We calculate the adiabatic Potential Energy Surfaces (PESs) and the Non-Adiabatic Coupling Terms (NACTs) for the three lowest singlet states of H-3(+) in hyperspherical coordinates as functions of hyperangles (0 and phi) for a grid of fixed values of hyperradius (1.5 <= rho <= 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 0-phi space, i.e., there are six Conical Intersections (CIs) at each 0 (60 degrees <= 0 <= 90 degrees) within the domain, 0 <= phi <= 2 pi. 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 rho = 10 bohrs, generally only those results are depicted. (C) 2014 AIP Publishing LLC.