A modification of the Monte Carlo method for simulation of radiative   transfer in molecular clouds
  We propose a method of simulation that is based on the averaging of formal solutions of the transfer equation by taking the integral by the Monte Carlo method. This method is used to compute two models, which correspond to the limiting cases of hot gas and cold background radiation and of hot background radiation and cold gas, for E-methanol emission from a compact homogeneous spherical region. We analyse model level populations by using rotational diagrams in the limiting cases mentioned above. Model optical depths of the lines with frequencies below 300 GHz up to J=11 inclusive are given. 
Maxim A. Voronkov (Astro Space Center, Moscow, Russia)