Description:
Define a computation that calculates the temperature of a group of -atoms, after subtracting out a spatially-averaged velocity field, -before computing the kinetic energy. This can be useful for -thermostatting a collection of atoms undergoing a complex flow, -e.g. via a profile-unbiased thermostat (PUT) as described in +atoms, after subtracting out a spatially-averaged center-of-mass +velocity field, before computing the kinetic energy. This can be +useful for thermostatting a collection of atoms undergoing a complex +flow, e.g. via a profile-unbiased thermostat (PUT) as described in (Evans). A compute of this style can be used by any command that computes a temperature, e.g. thermo_modify, fix temp/rescale, fix npt, etc. @@ -71,12 +71,12 @@ the bins are "tilted" slabs or pencils or bricks that are parallel to the tilted faces of the box. See the region prism command for a discussion of the geometry of tilted boxes in LAMMPS.
-When a temperature is computed, the velocity for the set of atoms that -are both in the compute group and in the same spatial bin is summed to -compute an average velocity for the bin. This bias velocity is then -subtracted from the velocities of individual atoms in the bin to yield -a thermal velocity for each atom. Note that if there is only one -atom in the bin, it's thermal velocity will thus be 0.0. +
When a temperature is computed, the center-of-mass velocity for the +set of atoms that are both in the compute group and in the same +spatial bin is calculated. This bias velocity is then subtracted from +the velocities of individual atoms in the bin to yield a thermal +velocity for each atom. Note that if there is only one atom in the +bin, its thermal velocity will thus be 0.0.
After the spatially-averaged velocity field has been subtracted from each atom, the temperature is calculated by the formula KE = dim/2 N k diff --git a/doc/compute_temp_profile.txt b/doc/compute_temp_profile.txt index 10f47919cb..20be9ac9ee 100644 --- a/doc/compute_temp_profile.txt +++ b/doc/compute_temp_profile.txt @@ -39,10 +39,10 @@ compute myTemp flow temp/profile 0 1 1 xyz 20 20 20 :pre [Description:] Define a computation that calculates the temperature of a group of -atoms, after subtracting out a spatially-averaged velocity field, -before computing the kinetic energy. This can be useful for -thermostatting a collection of atoms undergoing a complex flow, -e.g. via a profile-unbiased thermostat (PUT) as described in +atoms, after subtracting out a spatially-averaged center-of-mass +velocity field, before computing the kinetic energy. This can be +useful for thermostatting a collection of atoms undergoing a complex +flow, e.g. via a profile-unbiased thermostat (PUT) as described in "(Evans)"_#Evans. A compute of this style can be used by any command that computes a temperature, e.g. "thermo_modify"_thermo_modify.html, "fix temp/rescale"_fix_temp_rescale.html, "fix npt"_fix_nh.html, etc. @@ -61,12 +61,12 @@ the bins are "tilted" slabs or pencils or bricks that are parallel to the tilted faces of the box. See the "region prism"_region.html command for a discussion of the geometry of tilted boxes in LAMMPS. -When a temperature is computed, the velocity for the set of atoms that -are both in the compute group and in the same spatial bin is summed to -compute an average velocity for the bin. This bias velocity is then -subtracted from the velocities of individual atoms in the bin to yield -a thermal velocity for each atom. Note that if there is only one -atom in the bin, it's thermal velocity will thus be 0.0. +When a temperature is computed, the center-of-mass velocity for the +set of atoms that are both in the compute group and in the same +spatial bin is calculated. This bias velocity is then subtracted from +the velocities of individual atoms in the bin to yield a thermal +velocity for each atom. Note that if there is only one atom in the +bin, its thermal velocity will thus be 0.0. After the spatially-averaged velocity field has been subtracted from each atom, the temperature is calculated by the formula KE = dim/2 N k