The CHARMM package contains the main program that typically runs on Linux or Apple iOS computers along with force field parameters and test cases. CHARMM is written in modern Fortran 95 and interfaces with other packages if available.

Parallel execution is supported via MPI and openMP. A GPU version is available via an interface to the openMM package.

Major versions are released yearly in three different flavors:

  • charmm provides all of the functionality and can be downloaded for free for academic users.
  • CHARMM is a high-performance version supporting large-scale parallelism and GPUs and is available here for a modest fee.
  • CHARMm is the commercial version available through Biovia.


If you use CHARMM in your research, please cite the following paper:

B. R. Brooks, C. L. Brooks III, A. D. Mackerell, L. Nilsson, R. J. Petrella, B. Roux, Y. Won, G. Archontis, C. Bartels, S. Boresch A. Caflisch, L. Caves, Q. Cui, A. R. Dinner, M. Feig, S. Fischer, J. Gao, M. Hodoscek, W. Im, K. Kuczera, T. Lazaridis, J. Ma, V. Ovchinnikov, E. Paci, R. W. Pastor, C. B. Post, J. Z. Pu, M. Schaefer, B. Tidor, R. M. Venable, H. L. Woodcock, X. Wu, W. Yang, D. M. York, and M. Karplus: CHARMM: The Biomolecular simulation Program, J. Comp. Chem. 30, 1545-1615 (2009), 

The original CHARMM reference and a brief update are:

B. R. Brooks, R. E. Bruccoleri, B. D. Olafson, D. J. States, S. Swaminathan, and M. Karplus: CHARMM: A Program for Macromolecular Energy, Minimization, and Dynamics Calculations, J. Comp. Chem. 4, 187-217 (1983)

A. D. MacKerell, Jr., B. Brooks,C. L. Brooks, III, L. Nilsson, B. Roux, Y. Won, and M. Karplus: CHARMM: The Energy Function and Its Parameterization with an Overview of the Program, in The Encyclopedia of Computational Chemistry, 1, 271-277, P. v. R. Schleyer et al., editors (John Wiley & Sons: Chichester, 1998)