Thermostats
All NPT MD methods thermostat the momentum temperature
Proper sampling of the canonical ensemble requires that the momentum temperature fluctuates
- momentum temperature is proportional to total kinetic energy
- energy should fluctuate between K and U
- variance of momentum-temperature fluctuation can be derived from Maxwell-Boltzmann
fluctuations vanish at large N
rigidly fixing K affects fluctuation quantities, but may not matter much to other averages
All thermostats introduce unphysical features to the dynamics
- EMD transport measurements best done with no thermostat
use thermostat equilibrate r and p temperatures to desired value, then remove