Generalized diatomics-in-molecule method for polyatomics

A new derivation of the generalized diatomics-in-molecule (GDIM) method for the description of electronically stationary and quasi-stationary states of a polyatomic molecule is given in the partial-wave representation of the electron continuum. The method is based on the combination of the projection-operator approach of scattering theory with the diatomics-in-molecule fragmentation of the fixed-nuclei Hamiltonian, resulting in the construction of diabatic discrete states, electron-molecule scattering continua and discrete-continuum couplings from the corresponding data of the fragments. The GDIM method is applied to the H₃^- anion. The ground-state local-complex-potential surface (both the real and the imaginary parts) is obtained. Classical trajectories of H^-+H₂ collisions with inclusion of the electron detachment channel are calculated.