Ab initiocalculation of the 66 low-lying electronic states of HeH⁺: adiabatic and diabatic representations

Abstract

Using the quantum chemistry package MOLPRO and an adapted basis set, we have calculated the adiabatic potential energy curves of the first 20 1 + , 19 3 + , 12 1 , 9 3 , 4 1 and 2 3 electronic states of the HeH + molecular ion in CASSCF and CI approaches. The results are compared with previous works. The radial and rotational non-adiabatic coupling matrix elements as well as the dipole moments are also calculated. The asymptotic behaviour of the potential energy curves and of the various couplings between the states is also studied. Using the radial couplings, the diabatic representation is defined and we present an example of our diabatization procedure on the 1 + states.

Ab initiocalculation ofH+He+charge-transfer cross sections for plasma physics

“…the elements F m,m+1 . The main reason is that this approach simplifies considerably the diabatization procedure [24]. It has been shown to give similar results as when the complete F matrix is taken into account in dynamical calculations [26], something we have also observed in the low-energy calculation of the charge transfer cross sections for the n = 2 1 Σ + states (see below).…”

“…An adapted basis set consisting of the aug-cc-pv5Z basis set [23] supplemented by one contracted Gaussian function per orbital per atom up to n = 4 has been used. Details of the calculations can be found in [24]. Due to the electric field produced by He + (1s), there figure 1 for the n = 2 − 3 states.…”

Charge transfer in proton–helium collisions from low to high energy

“…Since the entrance channel in (1) and (2) is a singlet state, the triplet states of HeH + can be neglected. The molecular data were taken from [6], and details on the ab initio calculations can be found in this reference. The first method employed is time-dependent and is based on the propagation of a Gaussian wave packet on the PEC of the initial state.…”

Photodissociation and Radiative Association of HeH+ in the Metastable Triplet State

“…We adopted the molecular data presented in Ref. [25]. The potential energy curves, non-adiabatic couplings and dipole transition moments were calculated at the complete active space self-consistent field (CASSCF) and configuration interaction (CI) levels.…”

“…Due to the large number of such couplings, we do not show them here and refer the reader to Refs. [25,26] where they are discussed. The matrix of the radial non-adiabatic couplings in the basis of the adiabatic electronic functions {ζ m }, F mm ′ = ζ m |∂ R |ζ m ′ , can be used to build the diabatic representation [27].…”