Direct dissociative recombination of HCO+via the core-excited doublet and the lowest quartet states.

The dissociative recombination of HCO+ up to 1 eV collision energy is studied. New calculations for several core-excited HCO states provide improved potential energy surfaces crossing the HCO+ ground state surface in the vicinity of its equilibrium geometry. Wave packet analysis leads to significantly higher contributions of the direct mechanism to the cross section for electron energy ε < 0.7 eV than according to earlier studies [Larson et al., Phys. Rev. A, 2012, 85, 042702]. The limit H + CO(a3Π) is found to be the most probable exit channel. We discuss the improved agreement of theory with the latest experiments [Hamberg et al., J. Phys. Chem., 2014, 118, 6034] resulting from combination with the most recent calculations of the indirect process [Fonseca dos Santos et al., J. Chem. Phys., 2014, 140, 164308]. For the lowest quartet surfaces some vibrational states and their population and depopulation (mediated by spin-orbit coupling) are examined.