Based on the idea that different temperatures generate different carrier de
nsities and the resulting diffusion causes the thermal emf, a new formula f
or the Seebeck coefficient S is obtained: S = (2 ln 2/3)(qn)(-1) epsilon (F
)k(B)(N-o/V), where q, n, epsilon (F), N-o and V are respectively charge, c
arrier density, Fermi energy, density of states at epsilonF and volume. Ohm
ic and Seebeck currents are fundamentally different in nature. This differe
nce can cause significantly different transport behaviors. For a multi-carr
ier metal the Einstein relation between the conductivity and the diffusion
coefficient does not hold in general. Seebeck (S) and Hall (R-H) coefficien
ts in noble metals have opposite signs. This is shown to arise from the Fer
mi surface having "necks" at the Brillouin boundary.