RASPA: This software is a general purpose classical simulation package. It has been developed at Northwestern University (Evanston, USA) during 2006-2011 in active collaboration with University Pablo de Olavide (Seville, Spain), and the Technical University of Delft. It can be used for the simulation of molecules in gases, fluids, zeolites, aluminosilicates, metal-organic frameworks, carbon nanotubes and external fields.