In chemistry, a water cluster is a discrete hydrogen bonded assembly or cluster of molecules of water. Many such clusters have been predicted by theoretical models (in silico), and some have been detected experimentally, in various contexts such as ice, and bulk liquid water, in the gas phase, in dilute mixtures with non-polar solvents, and as water of hydration in crystal lattices. The simplest example is the water dimer (H2O)2. On the basis of the two state model proposed by Werner Luck it is suggested that the Raman spectrum for water can be explained on the basis of the presence of free and hydrogen bonded hydrogen bonds. The model Luck has application with spectral method Differential Non-equilibrium Energy Spectrum (DNES) by Anton Antonov.