These are the models we used in Leiden. ccurve.in this does a collisional ionization cooling function and is an example of using the "grid" to compute a number of models. ccurve.vsx is the veusz plotting program file we used to plot the results. During class I forgot to include galactic background cosmic rays. As a result the code struggled to converge the sims at low temperatures where the gas has a significant molecular content. The cosmic ray background is needed for the chemistry to converge at low temperatures. orion_hii_open.in This is the Orion Nebula model from the test suite - if you download a copy of the code it will be in cloudy / tsuite /auto star_kurucz_39600.dat is a Kurucz Atlas stellar atmosphere emergent SED. This is used to photoionize the H II region. The outer radius of the cloud is set by the point where the gas kinetic temperature falls below 4000 K - the default lowest kinetic temperature the code will consider. orion_hii_pdr.in This is a somewhat similar model to orion_hii_open.in but includes the PDR by lowering the lowest allowed temperature, which extends the calculation into warm / cold regions containing atomic and molecular hydrogen.