Summary

• Standard MD simulations are performed in the NVE ensemble

  • initial momenta can be set to desired temperature, but very hard to set configuration to have same temperature
  • momentum and configuration coordinates go into thermal equilibrium at temperature that is hard to predict

• Need ability to thermostat MD simulations

  • aid initialization
  • required to do NEMD simulations

• Desirable to have thermostat generate canonical ensemble

• Several approaches are possible

  • stochastic coupling with temperature bath
  • constraint methods
  • more rigorous extended Lagrangian techniques

• Barostats and other constraints can be imposed in similar ways

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