Photodissociation dynamics from the repulsive n sigma (C-X)* (X = Cl,Br) states of CBrClF2 has been studied by propagating wave packets on the two diabatic potential energy surfaces obtained by an approximate diabatization of ab initio complete active space self-consistent field (CASSCF) potential energy surfaces. The diabatization was carried out so as to eliminate the transition-dipole moment between the two excited states. The results have confirmed the occurrence of simultaneous triple dissociation CBrClF2-->Br+Cl+CF2 observed in the 157.6 nm photolysis of CBrClF2. The triple dissociation has been found to occur on both the upper and lower adiabatic surfaces with oscillation in the population in between. (C) 2001 American Institute of Physics.