Volume 114, Issue 12, 22 March 2001
Index of content:
Degenerate conical intersections: The interaction between the and electronic states of as a case study114(2001); http://dx.doi.org/10.1063/1.1356004View Description Hide Description
In this Letter are presented and analyzed conical intersections which appear on the two symmetric sides of the line of the molecule. Two conical intersections (CI) of this kind, between the and electronic states, were found to be only a short distance apart, e.g., ∼0.3 Å for the CC distance of 1.25 Å. It is shown that these two CIs—to be termed CI twins—have opposite “charges” thus forming altogether a weak interaction. By increasing the CC distance, to 1.35 Å, the two twins coalesce to form a single CI. The interaction of this merged pair varies with the distance as (as is the case for conical intersections) but, in contrast to ordinary CIs, does not exhibit any topological effects and its intensity is shown to be zero. These features led us to term it as a degenerate CI or concisely DCI.
114(2001); http://dx.doi.org/10.1063/1.1357203View Description Hide Description
The quantum trajectory method (QTM) is extended to the dynamics of electronic nonadiabiatic collisions. Equations of motion are first derived for the probability density, velocity, and action function for wave packets moving on each of the coupled electronic potential surfaces. These discretized equations are solved in the Lagrangian (moving with the fluid) picture to give the trajectory dynamics of fluid elements evolving on each potential surface. This trajectory method is fully quantum mechanical and does not involve “trajectory surface hopping.” The method is applied to nonadiabiatic collision models involving two coupled electronic states. The quantum trajectory results are in excellent agreement with solutions computed (using space-fixed grid methods) directly from the time-dependent Schrödinger equation.