The semirigid vibrating rotor target model for quantum polyatomic reactiondynamics

In this paper, we present detailed quantum treatment of the semirigid vibra ting rotor target (SVRT) model for reaction dynamics involving polyatomic m olecules. In the SVRT model, the reacting (target) molecule is treated as a semirigid vibrating rotor which can be considered as a three-dimensional g eneralization of the diatomic molecule. This model provides a realistic fra mework to treat reaction dynamics of polyatomic systems. Using the SVRT mod el, it becomes computationally practical to carry out quantitatively accura te quantum dynamics calculation for a variety of dynamics problems in which the reacting molecule is a polyatomic or complex molecule. In this work, s pecific theoretical treatment and mathematical formulation of the SVRT mode l are presented for three general classes of reaction systems: (1) reaction of an atom with a polyatomic molecule (atom-polyatom reaction), (2) reacti on between two polyatomic molecules (polyatom-polyatom reaction), and (3) p olyatomic reaction with a rigid surface (polyatom-surface reaction). Since the number of dynamical degrees of freedom in the SVRT model for the above three classes of dynamical problems is limited, accurate quantum (both ab i nitio and dynamical) calculations are possible for many reactions of practi cal chemical interest. In this paper, a time-dependent wave packet approach is employed to implement the SVRT model for dynamics calculation of polyat omic reactions. (C) 1999 American Institute of Physics. [S0021-9606(99)0313 3-5].