Coexistences and competitions of symmetry broken states in quasi-one-dimensional molecular conductors; A Finite-temperature study

Seo, Hitoshi; Kato, Takeo*; Motome, Yukitoshi*

We have theoretically investigated finite-temperature properties of quarter-filled molecular conductors with quasi-one-dimensional structures. They exhibit a large variety of electronic and electron-lattice coupled phases, and since the systems have similar noninteracting electronic structures, such a variety in their physical properties implies the importance of strong correlation effects. In this work, we aim at providing a unified view for these compounds by studying a electron-lattice coupled quasi-one-dimensional model. We apply two numerical methods to this model, by treating the lattice degree of freedom as classical variables. One is the quantum transfer matrix method applied to an effective one-dimensional model. Another is the quantum Monte Carlo simulation with stochastic series expansion where the interchain interaction as well as the thermal fluctuation of the lattice can be taken into account in an unbiased way. We will compare numerical results with experimental data at a quantitative level so as to elucidate the origin of the various properties seen in the actual compounds.