Cassandra is an open source Monte Carlo package being developed in the Maginn group at the University of Notre Dame.
Features
Cassandra is capable of simulating any number of molecules composed of rings, chains, or both. We have 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 can simulated the following ensembles: canonical (NVT), isothermal-isobaric (NPT), grand (muVT), osmotic (muPT), Gibbs (NVT and NPT versions), and reactive (RxMC). Cassandra is parallelized with openMP, and therefore runs efficiently on multi-core machines.
Some of the advanced sampling features have been described in a recent publication:
A general and efficient Monte Carlo method for sampling intramolecular degrees of freedom of branched and cyclic molecules, J. Shah and E. J. Maginn, J. Chem. Phys., 135, 134121 (2011)
Cassandra was modified and then used by Neeraj Rai to carry out the first VLE simulations of an ionic liquid. Read more about it in these publications:
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Neeraj Rai and Edward J. Maginn, “Critical Behaviour and Vapour-Liquid Coexistence of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide Ionic Liquids Via Monte Carlo Simulations”, Faraday Discussions, 2012, 154, 53-69.
Neeraj Rai and Edward J. Maginn, “Vapor-Liquid Coexistence and Critical Behavior of Ionic Liquids via Molecular Simulations”, Journal of Physical Chemistry Letters, 2011, 2, 1439-1443. [DOI: 10.1021/jz200526z ACS Articles on Request]
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Availability
We are still refining the interface and documentation of Cassandra, as well as trying to set up reasonable support for the code. As a result, we have not yet released Cassandra as a full open source code yet. We are interested in working with a small number of beta testers, however. If you are interested in this, please contact Ed Maginn (ed@nd.edu). We hope to release Cassandra as a full open source code later in 2012.
Where did Cassandra come from?
Cassandra evolved out of an academic code developed by Ed Maginn while he was a graduate student in the early 1990s. The code has been extended and refined in the Maginn group at Notre Dame since 1995. In 2007 while on sabbatical at the Computer Science Research Institute at Sandia National Laboratories, Ed were inspired by the success of the MD code LAMMPS (developed at Sandia) to re-write this code to make it a general purpose Monte Carlo code. Prof. Jindal Shah took the lead role in the development of the code, and Cassandra was born. It is now maintained and extended at Notre Dame by a team of postdocs and graduate students, with significant contributions coming from Neraaj Rai and Andrew Paluch.
Where did the name Cassandra come from?
In Greek mythology, Cassandra was the beautiful daughter of King Priam and Queen Hecuba of Troy. As the story goes, Cassandra fell asleep in Apollo’s temple and, this being Greek mythology, Apollo made advances toward her. She resisted, and so as punishment Apollo gave her the power of accurate prophecy, but also cursed her so that nobody believed her predictions. Cassandra was then left with the knowledge of future events, but she could not convince others that her predictions would come true. When a strange horse appeared in Troy, Cassandra warned her father that the Greeks would use the horse to take control of Troy. Of course, he didn't believe her, and the rest is history. After the fall of Troy, Cassandra was abducted by Agamemnon and taken to Mycenae on Crete, where she was eventually killed by Clytemnestra. Of course, she knew all this would happen. We think Cassandra also has great predictive powers, but we hope you will take its predictions more seriously than those ancient Trojans. We really wanted to use this name for our code, so we made up the proper acronym: Cassandra stands for Computational Atomistic Simulation Software At Notre Dame for Research in Academia. How about that?
CASSANDRA Developers Schedule - Fall 2012
CASSANDRA users / developers will meet on the following days:
Sept 6, Sept 27, Oct. 25, Nov. 15, Dec 13. All meetings will be at noon in Conference Room 1 in the COMSEL Lab, 150 Fitzpatrick. Eliseo is the overall coordinator.
Cassandra image: Evelyn de Morgan [Public domain], via Wikimedia Common