# MCNP multigroup scattering matrix and diffusion coefficient

Hello

I am a lower-intermediate user of MCNP and I do not know how to obtain the diffusion coefficient (or maybe the angle of scattering) using tallies. I also have read a paper (Multigroup Scattering Matrix Generation Method using Weight-to-Flux Ratio Based on a Continous Energy Monte Carlo Technique) in which the multigroup scattering matrix is calculated using weight-to-flux ratio but i am not sure if the weight can be calculated employing a F1 tally. In this same paper says that one can calculate the angle of scattering with tallies and with these results the mean scattering angle can be obtained, but I have no idea how the scattering angle is obtained with the tallies. Hope you can help me. Thanks