CHARMm (Chemistry at HARvard Macromolecular Mechanics) is a highly regarded and widely used simulation package. CHARMm combines standard minimization and dynamics capabilities with expert features including normal mode calculations, correlation analysis, and combined quantum and molecular mechanics (QM/MM) methods. Simulations provide information concerning molecular-level structure, interactions, and energetics. Originally developed in the laboratory of Professor Martin Karplus at Harvard University, this program allows you to perform classical empirical energy calculations on a variety of small and large molecular systems, including proteins, nucleic acids, and carbohydrates. Using the latest algorithms and methodology, you can explore in detail the dynamics and thermodynamics of your system of interest, providing insight into your current experiments and suggesting new directions for future efforts.

CHARMm has the ability to restart calculations from information saved to files.