If the crystal is in dynamic equilibrium with its parent phase the free energy is at a minimum and no growth will occur. For growth to occur this equilibrium must be disturbed by a change of the correct sign, in temperature, pressure, chemical potential (e. g. saturation), electrochemical potential (e. g. electrolysis), or strain (solid state growth). The system may then release energy to its surroundings to compensate for the decrease in entropy occasioned by the ordering of atoms in the crystal and the evolution of heat of crystallization. In a well-designed growth process just one of these parameters is held minimally away from its equilibrium value to provide a driving force for growth.
