The Pariser-Parr-Pople model of pi-conjugated electrons is solved by the
density matrix renormalization group method for the light emitting polymer,
poly(para-phenylene vinylene). The energies of the primary excited states are
calculated. When solid state screening is incorporated into the model
parameters there is excellent agreement between theory and experiment, enabling
an identification of the origin of the key spectroscopic features.Comment: 6 pages, 3 figure