  We calculate the linear response thermopower S of a quantum point contact
using the Landauer formula and therefore assume non-interacting electrons. The
purpose of the paper, is to compare analytically and numerically the linear
thermopower S of non-interacting electrons to the low temperature
approximation, S^1=(pi^2/3e)k^2 T d(ln G(mu,T=0))/dmu, and the so-called Mott
expression, S^M=(pi^2/3e)k^2 T d(ln G(mu,T))/dmu, where G(mu,T) is the
(temperature dependent) conductance. This comparison is important, since the
Mott formula is often used to detect deviations from single-particle behavior
in the thermopower of a point contact.
