Welcome to SSAGES!

In their simplest form, particle-based simulations are limited to generating ensembles of configurations (in Monte Carlo [MC] simulations) or trajectories in time (in molecular dynamics [MD] or Brownian dynamics [BD]). One can then extract mechanical variables such as the potential energy or pressure and perform ensemble or time averages. There are two important limitations to such calculations:

  1. For complex materials, the time scales available to standard MD simulations are often insufficient to sample relevant regions of phase space

  2. In order to develop a fundamental understanding of materials, researchers are primarily interested in calculating the free energy, the entropy, and their derivatives with respect to various thermodynamic quantities (which lead to material properties such as elastic moduli, heat capacity, and various other susceptibilities).

These quantities are difficult to obtain or intractable in standard MC and MD simulations. To overcome these limitations, MC and MD simulations must be supplemented with advanced sampling techniques. These methods are critical for the efficient simulation of complex assembly processes.

SSAGES (Software Suite for Advanced General Ensemble Simulations) is designed to perform these calculations. The framework is designed to treat molecular simulation routines as a black box, using the coordinates of the system as evolved by an MD engine to compute collective variables which permit a meaningful reduced-dimensionality representation of the phase space within a system. This information is then used to define evolving reactive pathways or to bias the statistics of a simulation for the purposes of computing free energies. The internal structure of the code has been designed to be simple and extensible to new sampling methods and engines. For further details on examples and capabilities of SSAGES, peruse the documentation for specific methods.


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