The effects of quantum lattice fluctuations on nonlinear optics of polyacetylene

The effects of quantum lattice fluctuations on nonlinear optics in the Su-Schrieffer-Heeger (SSH) model are studied using the quantum Monte Carlo (QMC) method. We find that the magnitude of χ(3) is increased by a factor 18 by the quantum lattice fluctuations. This effect mainly comes from the quantum lattice fluctuations of charged soliton-antisoliton pairs.