Collision-induced intramolecular energy flow and fragmentation in van der Waals complexes: Atom+tetramer collisions.

Intramolecular energy flow and fragmentation processes in a linear van der Waals complex consisting of four molecular units undergoing collision with an incident atom are studied by solving Hamilton’s equations of motion for positions and momenta of all molecular units and van der Waals bonds. Numerical results are obtained for an O2 tetramer, which is in interaction with an argon atom: Ar+(1–2···3–4···5–6···7–8). Energy flow is found to be very efficient, and above the fragmentation threshold most of the energy transferred to the complex through the collision of the first unit (1–2) of the complex with Ar is found to become localized at the terminal van der Waals bond 5–6···7–8, the dissociating mode, thus causing the end molecular unit (7–8) to break off. Short-time dynamics of energy buildup in each molecular unit and van der Waals bond is analyzed in detail. [ABSTRACT FROM AUTHOR]