Isoenthalpic–isobaric ensemble

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The isoenthalpic-isobaric ensemble (constant enthalpy and constant pressure ensemble) is a statistical mechanical ensemble that maintains constant enthalpy and constant pressure applied. It is also called the -ensemble, where the number of particles is also kept as a constant. It was developed by physicist H. C. Andersen in 1980.[1] The ensemble adds another degree of freedom, which represents the variable volume of a system to which the coordinates of all particles are relative. The volume becomes a dynamical variable with potential energy and kinetic energy given by .[2] The enthalpy is a conserved quantity.[3]


  1. ^ Andersen, H. C. Journal of Chemical Physics 72, 2384-2393 (1980).
  2. ^ Hwee, Chiang Soo. "Mechanical behavior of peptides in living systems using molecular dynamics."
  3. ^ Other Statistical Ensembles