On the intersection of potential energy surfaces in charge transfer reactions: A crossing seam for two states of the same symmetry in the reaction H++NO(X 2Π)→H(2S)+NO+(X 1Σ+)

An actual crossing seam of two potential energy surfaces of the same symmetry relevant to the charge transfer reaction H++NO(X 2Π)→H(2S)+NO+(X 1Σ+) is reported. This crossing seam occurs for general Cs geometries. It represents the intersection of the 1,2 2A′ potential energy surfaces which correlate asymptotically with H(2S)+NO+(X 1Σ+) and H++NO(X 2Π), respectively. A portion of the seam is exoergic relative to the reactant channel, H++NO(X 2Π), asymptote. The present results complement a previous determination of two allowed crossing seams in C∞v symmetry, and provide, for the first time, an example of a system for which both allowed and actual conical intersections exist. Since the actual crossing seam occurs for geometrical configurations quite distinct from the allowed crossing seams previously considered these results have important implications for the rotational–vibrational energy distribution in the products of the charge exchange process.