On the Quantization of the Electronic Non-Adiabatic Coupling Terms: The H+H2 System as a Case Study

Abstract

In this article we present a survey of the various conical intersections which govern potential transitions between the three lower electronic states for the title molecular system. It was revealed that these three states, for a given fixed HH distance, RHH, usually form four conical intersections: two between the two lower states and two between the two upper states. One of the four is the well-known equilateral D3h ci and the others are, essentially, C2v cis: One of them is located on the symmetry line perpendicular to the HH axis (like the D3h ci) and the other two are located on both sides of this symmetry line and in this way form the twin C2v cis. The study was carried out for two RHH-values, namely, RHH=0.74 and 0.4777 Å.The second subject treated here, in some detail, is related to the possible quantization of the non-adiabatic coupling matrix. We show that in general for small enough regions surrounding a particular ci the two-state quantization is fulfilled. However, increasing the region surrounded by the contour shows larger and larger deviations from the two-state quantization but then the three-state quantization shows relevance as expected from pure theoretical considerations (Baer and Alijah, Chem. Phys. Lett. 319, 489 (2000)).KeywordsConfiguration SpaceConical IntersectionSymmetry LineTopological PhaseCircular ContourThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.