About OOPSE OOPSE News Features Download CVS Mailing Lists Documentation Authors Funding Results	Constant pressure in 3 axes (NPTxyz) There is one additional extended system integrator which is somewhat simpler than the NPTf method described above. In this case, the three axes have independent barostats which each attempt to preserve the target pressure along the box walls perpendicular to that particular axis. The lengths of the box axes are allowed to fluctuate independently, but the angle between the box axes does not change. The equations of motion are identical to those described above, but only the diagonal elements of $\overleftrightarrow{\eta}$ are computed. The off-diagonal elements are set to zero (even when the pressure tensor has non-zero off-diagonal elements). It should be noted that the NPTxyz integrator is not known to preserve any Hamiltonian of interest to the chemical physics community. The integrator is extremely useful, however, in generating initial conditions for other integration methods. It is suitable for use with liquid simulations, or in cases where there is orientational anisotropy in the system (i.e. in lipid bilayer simulations).
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	Updated on January 16, 2006