Dynamics and Photoexcitation in MX and MXX' Chain Solids

摘要

Nonlinear adiabatic dynamics associated with nonlinear excitations in MX and MXXchain materials are numerically studied within a discrete, 3/4-filled, two-band, tight-binding extended Peierls-Hubbard model. Both Hartree-Fock (HF) adiabatic molecular relaxation and molecular dynamics techniques are employed to investigate the time evolution of solitons, polarons, bipolarons in charge-density wave (CDW), bond order wave (BOW), and spin-density-wave (SDW) ground state materials. Photoexcitations are performed between (1) continuum levels, (2) localized levels, (3) continuum and localized level. The subsequent formation and time evolution of excitons, defect pairs, breathers, and, for the MXX solids, charge separation are studied in terms of energy levels and distortion patterns. These results are compared with the dynamics of previously studied 1/2-filled, one band, SSH-type electron-photon models, used for studying polyenes and polyynes, and experimental data.