Hi Gary, Before I start hacking into the multi-processor package, I was wondering if you know of a way of pre-sending data to slave processors using the current design? The reason is because I would like to have the parallelisation at the lowest level of the target function. But there is a massive quantity of data which doesn't change at the target function level which would be better to transmit to and store on the slaves prior to optimisation (atomic positions, bond vectors, base NMR data, missing data flags, etc.). This is required to keep the data transmission of the slave_command objects from killing scalability. Any ideas? Cheers, Edward