Kinetic coefficients in a system far from equilibrium

The kinetic coefficients in a growing surface are very different from their equilibrium values. Assuming deposition of particles from a beam on an initially flat surface of high symmetry orientation and neglecting evaporation, the kinetic coefficients K-0 and X-0 relevant at the beginning oi the growth are evaluated in 1+1 and 2+1 dimensions. K-0 is the sum of three terms: i) a term coming from an "equilibrium" chemical potential, which vanishes with temperature but diverges at low flux in the case of a singular surface; ii) a term, whose origin is the random character of nucleation, which defends only on the beam intensity and the diffusion constant but is independent of the atomic distance; iii) a term deriving from the fluctuations of the diffusion current: which depends on the beam intensity, the diffusion length, and the atomic distance and, in 1+1 dimensions, only depends on the temperature through the diffusion length. The validity of a linear equation is limited to small slopes \m\ < 1/l(c) where l(c) is the maximum terrace width.