Isoenthalpic–isobaric ensemble explained
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] Using isoenthalpic-isobaric ensemble of Lennard-Jones fluid, it was shown
[4] that the Joule–Thomson coefficient and inversion curve can be computed directly from a single
molecular dynamics simulation. A complete vapor-compression refrigeration cycle and a vapor–liquid coexistence curve, as well as a reasonable estimate of the supercritical point can be also simulated from this approach.NPH simulation can be carried out using
GROMACS and
LAMMPS.
References
- Andersen, H. C. Journal of Chemical Physics 72, 2384-2393 (1980).
- Hwee, Chiang Soo. "Mechanical behavior of peptides in living systems using molecular dynamics."
- http://www.fisica.uniud.it/~ercolessi/md/md/node43.html Other Statistical Ensembles
- Kioupis, L. I.; Arya, G.; Maginn E. I. Pressure-enthalpy driven molecular dynamics for thermodynamic property calculation II: applications. Fluid Phase Equilibria 200, 93–110 (2002).http://nanoweb.ucsd.edu/~arya/paper4.pdf
