Using block diagonalization to determine dissociating autoionizing states: Application to N2H, and the outlook for SH

D. Kashinski (1) , Dahbia Talbi (2, 3) , A. P. Hickman (4)

1 USMA - United States Military Academy [West Point]
2 LUPM - Laboratoire Univers et Particules de Montpellier
3 AS
4 Lehigh USA

We describe our implementation of the block diagonalization method for calculating the potential surfaces necessary to treat dissociative recombination (DR) of electrons with N2H+. Using the methodology we have developed over the past few years, we performed multi-reference, configuration interaction calculations for N2H+ and N2H with a large active space using the GAMESS electronic structure code. We treated both linear and bent geometries of the molecules, with N2 fixed at its equilibrium separation. Because of the strong Rydberg-valence coupling in N2H, it is essential to isolate the appropriate dissociating, autoionizing states. Our procedure requires only modest additional effort beyond the standard methodology. The results indicate that the crossing between the dissociating neutral curve and the initial ion potential is not favorably located for DR, even if the molecule bends. The present calculations thereby confirm our earlier results for linear N2H and reinforce the conclusion that the direct mechanism for DR is likely to be inefficient. We also describe interesting features of our preliminary calculations on SH.

Mots clés: Diabatisation; Potential energy surfaces; Quantum chemical calculations; Electronic dissociative recombination

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Chimie-Physique [physics.chem-ph]

D. Kashinski, Dahbia Talbi, A. P. Hickman. Using block diagonalization to determine dissociating autoionizing states: Application to N2H, and the outlook for SH. EPJ Web of Conferences, 2015, DR2013: Ninth International Conference on Dissociative Recombination: Theory, Experiment, and Applic, 84, pp.03003. ⟨10.1051/epjconf/20158403003⟩. ⟨hal-01117212⟩