  We show that stimulated scattering of an isolated system of N Bose particles
with initially broad energy distribution can yield condensation of particles
into excited collective state in which most of the bosons occupy one or several
modes. During condensation, the total particle number and energy are conserved,
while entropy of the system grows. Onset of condensation occurs at a critical
particle occupation number when spectrum narrowing due to stimulated processes
overcomes spectrum broadening due to diffusion. This differs from Bose-Einstein
condensation in which particles undergo condensation into the equilibrium state
due to thermalization processes.
