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A Python framework for automated small molecule free energy driven design.
PERSES is a Python framework that uses OpenMM for GPU-accelerated molecular design driven by alchemical free energy calculations.
Perses performs relative free energy calculations using a single topology method. Single topology methods are those where the two ‘things’ that are being compared are done so by generating a single object whose parameters are perturbed between a representation of thing A to thing B. Perses supports perturbations between small molecules (for relative binding or relative hydration free energy calculations) and protein residues (resistance mutations).
Setting up and running a perses calculations involves three main stages.
Determining the atom-mapping of ligand A onto ligand B to work out the 2D topology of the single-topology alchemical object. Herein, alchemical topologies, systems, geometries etc. will be referred to as hybrid. This is handled by a
From this 2D hybrid topology, we then generate a 3D hybrid system. We use the input topology and coordinates for ligand A and the system and use RJMC to build in the atoms of ligand B. This is handled by a
With the hybrid system and hybrid topology, it’s possible to perform free energy calculations. Equilibrium methods such as REPEX and SAMS or non-equilibrium switching can be used. The method in which ligand A and ligand B are perturbed is handled by the
LambdaProtocol, and sampled using samplers such as
- Alchemical transformations
- Bias engine
- Molecular geometry generation via RJMC
- Sampler stack
- Storage handling