# Thermodynamic and Sampler States¶

The module openmmtools.states contains classes to maintain a consistent state of the simulation.

• ThermodynamicState: Represent and manipulate the thermodynamic state of OpenMM System and Context objects.
• SamplerState: Represent and cache the state of the simulation that changes when the System is integrated.
• CompoundThermodynamicState: Extend the ThermodynamicState to handle parameters other than temperature and pressure through the implementations of the IComposableState abstract class.
• GlobalParameterState: An implementation of IComposableState specialized to control OpenMM forces’ global parameters.
• GlobalParameterFunction: Allow enslaving a global parameter to arbitrary variables and mathematical expressions.

## States¶

 ThermodynamicState Thermodynamic state of a system. SamplerState State carrying the configurational properties of a system. CompoundThermodynamicState Thermodynamic state composed by multiple states. IComposableState A state composable through CompoundThermodynamicState. GlobalParameterFunction A function of global parameters. GlobalParameterState A composable state controlling one or more OpenMM Force’s global parameters.