I have used MOE, Discovery Studio and Ligand Scout for Pharmacophore screening of large databases using clusters and was happy with that. But now I changed to another place with very low budget so we can not buy these academic licenses anymore. Therefore I wonder if you could recommend me open source (or free) pharmacophore screening software, where both database generation and screening can be carried out in a cluster (in this aspect, what I basically need is that processed can be separated individually, and then results merged together)