Thermoelectric power in one-dimensional Hubbard model

Abstract

The thermoelectric power $S$ is studied within the one-dimensional Hubbard model using the linear response theory and the numerical exact-diagonalization method for small systems. While both the diagonal and off-diagonal dynamical correlation functions of particle and energy current are singular within the model even at temperature $T>0$, $S$ behaves regularly as a function of frequency $\ensuremath{\omega}$ and $T$. Dependence on the electron density $n$ below the half-filling reveals a change of sign of $S$ at ${n}_{0}=0.73\ifmmode\pm\else\textpm\fi{}0.07$ due to strong correlations, in the whole $T$ range considered. Approaching half-filling $S$ is holelike and can become large for $U⪢t$ although decreasing with $T$.