Quantum control of chemical reaction dynamics in a classical way

A simplified approach to quantum control of chemical reaction dynamics base d on a classical, local control theory was developed. The amplitude of the control pulse is proportional to the linear momentum of the reaction system within the dipole approximation for the system-radiation field interaction . The kinetic energy of the system is the controlling parameter. That is, t he reaction is controlled by accelerating the representative point on a pot ential energy surface before crossing over a potential barrier and then by deaccelerating it to the target after passing over the potential barrier. T he classical treatment was extended to control of wave packet dynamics by r eplacing the classical momentum by a quantum mechanically averaged momentum on the basis of the Ehrenfest theorem. The present method was applied to a quantum system of a simple one-dimensional, double-well potential for chec king its validity. A restriction of the applicability of the simplified met hod was also discussed. An isomerization of HCN was treated as a model syst em for wave packet control of a two-dimensional reaction. (C) 2000 American Institute of Physics. [S0021-9606(00)01033-3].