Pontibus system creation and solvation utilities

Utility methods for creating systems in Pontibus Protocols.

System creation

Methods used to build systems with OpenFF Interchange & OpenMM.

interchange_system_creation

Create an Interchange object for a given system, solvating with packmol where necessary.

System solvation

Methods used to solvate systems with either packmol or openmm through OpenFF Intercahnge.

packmol_solvation	Solvate solute Topology using the Interchange packmol interface.
openmm_solvation	Solvate solute Topology using OpenMM's Modeller.