Genuine saddle point and nucleation potential for binary systems

A generalized nucleation potential is constructed for binary systems. The p otential consists of the reversible work of cluster formation plus addition al terms arising from various kinetic effects. We show that the major nucle ation flux passes through the saddle point (termed the genuine saddle point ) of this generalized nucleation potential. The generalized nucleation pote ntial reduces to the kinetic potential of a unary system when one component vanishes. The genuine saddle point concept provides a convenient way to id entify systems and conditions for which the ridge crossing phenomenon occur s. Our theory agrees approximately with exact numerical results.