I guess we should have SMC-ABC in PyMC3 in no more than a week.
@mjclarke94 in SMC-ABC-speak your “atomistic modelling program” is call a simulator SMC-ABC starts by passing a set of parameters from a prior distribution (your “rough ideas from literature”) to the simulator and then comparing the results of the simulator to the observed/experimental values. Then the set of proposed parameters is refined iteratively in order to make the simulated data and the observed data come closer.
To use SMC-ABC you will need to call your “atomistic modelling program” from Python. If you can share the data and “atomistic modelling program” then I could try to see how well SMC-ABC works for your problem, otherwise we will let you know when SMC-ABC becomes available on PyMC3 and you will be able to try it by yourself.