What is the Langevin equation used for?
In physics, a Langevin equation (named after Paul Langevin) is a stochastic differential equation describing how a system evolves when subjected to a combination of deterministic and fluctuating (“random”) forces.
What is the difference between canonical ensemble and grand canonical ensemble?
The key difference between canonical and grand canonical ensemble is that a canonical ensemble describes a system in thermal equilibrium with a heat reservoir at a given temperature, whereas a grand canonical ensemble describes a system in contact with both a heat reservoir and a particle reservoir.
What is the difference between NVE and other ensembles?
In my opinion, NVE ensemble contains more thermodynamical information than any other ensemble, precisely, because of it is more close to the exact microscopic dynamics of the isolated system. You can see more about ensemble inequivalence in the Gross books “Microcanonical thermodynamics”.
Should I use different ensembles for different stages of simulation?
depends on if you believe that your system will like change its shape during simulation time. In my opinion you use the following ensembles at different stages.
How do I obtain the microcanonical or NVE ensemble of VASP?
Requests for technical support from the VASP group should be posted in the VASP-forum . The microcanonical or NVE ensemble can be obtained in the following ways: Set SMASS =-3 and specifying MDALGO =2 (or 0). Set ANDERSEN_PROB =0.0 while using the Andersen thermostat ( MDALGO =1).
What are the available ensembles in the discover 95 program?
Constant temperature, constant volume(NVT) (default). Constant temperature, constant pressure(NPT). In the Discover 95.0program, the available ensembles are: Constant energy, constant volume(NVE). Constant temperature, constant volume(NVT) (default). Constant temperature, constant pressure(NPT). Constant temperature, constant stress(NST).