Soliton dynamics intrans-polyacetylene using the full Pariser-Parr-Pople Hamiltonian

Soliton dynamics applying the full Pariser-Parr-Pople (PPP) Hamiltonian is presented. A (CH${)}_{29}$ model chain is used. From these first calculations in the PPP Hamiltonian it is deduced that the best expression for the electron-electron interaction is the Ohno formula with an on-site Hubbard term U=11.08 eV for carbon. The kinetic mass of the soliton turned out to be roughly twice the value obtained from Su-Schrieffer-Heeger (SSH) calculations. The soliton velocity is smaller than that in the (SSH) model; its half-width is reduced from 7 to ≊3 upon inclusion of electron-electron interaction. This value compares well with modified neglect of differential overlap results found in the literature. Analytic gradients are used and tested in the simulations.