Energy-Momentum Relation for Weakly Coupled Optical Polarons
Tianwei Wu, K. Y. Yang · Physical Review Letters · 1972
We have investigated the energy-momentum relationship for optical polarons by taking into consideration the phonon-cross-exchange diagrams. Our result is similar to that of the improved Tamm-Dancoff method, except that the whole curve shifts downward. Therefore, the ground-state energy is lower than the upper bound obtained by the variational method.