Distribution of the gas at the end of the relaxation phase. The density–temperature diagram corresponds to RelaxChem (this distribution does not change when gravity is included, apart from extending to higher densities as the gas collapses), with the red line representing the average temperature, and the green line the average dust temperature. The temperature-only distribution in the right-hand panel shows the typical temperature of the gas, 100–200 K, which is higher than the typical temperature assumed in isothermal molecular cloud simulations. In the top panel we show instead the density distribution for both relaxation models, where RelaxChem, extending to higher densities because of cooling, is shown in blue, and RelaxIso, more concentrated around the initial density, in orange.