Molecular Dynamics in Other Ensembles
Standard MD samples the NVE ensemble
There is need enable MD to operate at constant T and/or P
- with standard MD it is very hard to set initial positions and velocities to give a desired T or P with any accuracy
NPT MD permits control over state conditions of most interest
- NEMD and other advanced methods require temperature control
Two general approaches
- stochastic coupling to a reservoir
- feedback control
Good methods ensure proper sampling of the appropriate ensemble