Nonlinear optical response of MX chains in a one-band extended Peierls-Hubbard model

We study the nonlinear optical (NLO) response of quasi-one-dimensional electronic materials with both the electron-phonon and electron-electron interactions using a discrete, 12-filled, one-band, tight-binding extended Peierls-Hubbard model. Specifically, the variation of (i) photoinduced absorption, (ii) electroabsorption and (iii) third-order nonlinear optical susceptibility (χ(3)) as a function of electronic correlation (Hubbard parameters U, V) is studied systematically within single configuration intetaction (CI). These results are generic to low-dimensional materials such as conducting polymers. However, for relevant choice of parameters here we apply them to the case of MX chains. The predicted NLO response is compared with available experimental data on the strong charge-density-wave (CDW) MX material PtCl.