|From:||Axel Kohlmeyer <akohlmey@...24...>|
|Date:||Mon, 28 Aug 2017 16:02:03 -0400|
it is a case of "better safe than sorry". you can have only one fix changing the cell shape and volume, and that has to be coupled to the complete system pressure. that is usually for group all, i.e. what the thermo press keyword outputs. that should be done correctly by the npt or nph fix, but there is no harm in making it explicit.Interestingly with iso or aniso pressure I am able to have more than one fix npt without any errors or warnings. If I do:fix 1 rigidGroup rigid/nvt molecule temp 1.0 1.0 0.5fix 2 nonRigidGroup npt temp 1.0 1.0 0.5 iso 5.0 5.0 5.0Is that the same as the following practically speaking?fix 1 rigidGroup rigid/npt molecule temp 1.0 1.0 0.5 iso 5.0 5.0 5.0fix 2 nonRigidGroup npt temp 1.0 1.0 0.5 iso 5.0 5.0 5.0
The manual says that I "cannot" use both "fix npt" and "fix rigid/npt" since only one is coupled to system pressure, so I would have expected an error message. Is the last example above supported by LAMMPS or should it be avoided?