The effects of collective modes on the thermoelectric properties of a charge density system is studied. We derive the temperature dependences of thermoelectric power and thermal conductivity by applying the linear response theory to the Fröhlich Hamiltonian. Energy dissipation has been attributed to the nonlinear interaction between the phase mode and the amplitude mode, ignoring disorder effects. We have found that the temperature dependence of the correlation function between electrical and heat currents is the same as that of the correlation function between electrical currents. This implies that thermoelectric power is inversely proportional to temperature. We have also found that the temperature dependences of all correlation functions are essentially determined by the same mechanism - nonlinear amplitude-phase interaction. The thermal conductivity is nearly constant at a temperature above the amplitude mode gap, and is exponentially low at a temperature sufficiently below it.
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