Simulating gas-liquid and liquid-solid phase equilibria for ionic liquid systems is extremely challenging. Over the years we have developed a number of powerful simulation methods to tackle this and other hard molecular simulation problems, but we typically implemented the methods in locally used codes. Despite the fact that our papers explained how to implement these methods, few groups adopted our algorithms because of the difficulties involved. We then began implementing some of the methods in the open source molecular dynamics code LAMMPS and found that a lot more people were willing to give these methods a try.Inspired by LAMMPS, we have developed an open source atomistic Monte Carlo package called Cassandra. Cassandra is capable of simulating any number of molecules composed of rings, chains, or both. It can be used it to simulate small organic molecules, oligimers, and ionic liquids. It handles a standard 'Class I'-type force field having fixed bond lengths, harmonic bond angles and improper angles, a CHARMM or OPLS-style dihedral potential, a Lennard-Jones 12-6 potential and fixed partial charges. Cassandra uses OpenMP parallelization and comes with a number of scripts, utilities and examples to help with simulation setup. In this talk, I will describe the capabilities of Cassandra and show examples of some of the types of systems that can be simulated. I will also give performance information and describe how other users can contribute to making the code even better.

On the development of advanced Monte Carlo and molecular dynamics sampling methods, and how to get other people to use them

248th National Meeting (2014)

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