Self-trapping line of the Holstein molecular crystal model in one dimension

The ground state of the Holstein molecular crystal model of a single electr on in one dimension is studied using the Global-Local variational method, a nalyzing in particular the total energy, kinetic energy, phonon energy, and interaction energy over a broad region of the polaron parameter space. Thr ough the application of objective criteria, a curve is identified that simp ly, accurately, and robustly locates the self-trapping transition separatin g small polaron and large polaron behavior. Particular attention is given t o the kinetic energy, which is compared quantitatively with other perturbat ive and nonperturbative methods. [S0163-1829(99)16631-1].