<li>ID, group-ID are documented in <aclass="reference internal"href="fix.html"><spanclass="doc">fix</span></a> command</li>
<li>nvt/sllod = style name of this fix command</li>
<li>additional thermostat related keyword/value pairs from the <aclass="reference internal"href="fix_nh.html"><spanclass="doc">fix nvt</span></a> command can be appended</li>
<p>Perform constant NVT integration to update positions and velocities
each timestep for atoms in the group using a Nose/Hoover temperature
thermostat. V is volume; T is temperature. This creates a system
trajectory consistent with the canonical ensemble.</p>
<p>This thermostat is used for a simulation box that is changing size
and/or shape, for example in a non-equilibrium MD (NEMD) simulation.
The size/shape change is induced by use of the <aclass="reference internal"href="fix_deform.html"><spanclass="doc">fix deform</span></a> command, so each point in the simulation box
can be thought of as having a “streaming” velocity. This
position-dependent streaming velocity is subtracted from each atom’s
actual velocity to yield a thermal velocity which is used for
temperature computation and thermostatting. For example, if the box
is being sheared in x, relative to y, then points at the bottom of the
box (low y) have a small x velocity, while points at the top of the
box (hi y) have a large x velocity. These velocities do not
contribute to the thermal “temperature” of the atom.</p>
<divclass="admonition note">
<pclass="first admonition-title">Note</p>
<pclass="last"><aclass="reference internal"href="fix_deform.html"><spanclass="doc">Fix deform</span></a> has an option for remapping either
atom coordinates or velocities to the changing simulation box. To use
fix nvt/sllod, fix deform should NOT remap atom positions, because fix
nvt/sllod adjusts the atom positions and velocities to create a
velocity profile that matches the changing box size/shape. Fix deform
SHOULD remap atom velocities when atoms cross periodic boundaries
since that is consistent with maintaining the velocity profile created
by fix nvt/sllod. LAMMPS will give an error if this setting is not
consistent.</p>
</div>
<p>The SLLOD equations of motion, originally proposed by Hoover and Ladd
(see <aclass="reference internal"href="#evans"><spanclass="std std-ref">(Evans and Morriss)</span></a>), were proven to be equivalent to
Newton’s equations of motion for shear flow by <aclass="reference internal"href="#evans"><spanclass="std std-ref">(Evans and Morriss)</span></a>. They were later shown to generate the desired
velocity gradient and the correct production of work by stresses for
all forms of homogeneous flow by <aclass="reference internal"href="#daivis"><spanclass="std std-ref">(Daivis and Todd)</span></a>. As
implemented in LAMMPS, they are coupled to a Nose/Hoover chain
thermostat in a velocity Verlet formulation, closely following the
implementation used for the <aclass="reference internal"href="fix_nh.html"><spanclass="doc">fix nvt</span></a> command.</p>
<p>Additional parameters affecting the thermostat are specified by
keywords and values documented with the <aclass="reference internal"href="fix_nh.html"><spanclass="doc">fix nvt</span></a>
command. See, for example, discussion of the <em>temp</em> and <em>drag</em>
keywords.</p>
<p>This fix computes a temperature each timestep. To do this, the fix
creates its own compute of style “temp/deform”, as if this command had
<p>See the <aclass="reference internal"href="compute_temp_deform.html"><spanclass="doc">compute temp/deform</span></a> command for
details. Note that the ID of the new compute is the fix-ID +
underscore + “temp”, and the group for the new compute is the same as
the fix group.</p>
<p>Note that this is NOT the compute used by thermodynamic output (see
the <aclass="reference internal"href="thermo_style.html"><spanclass="doc">thermo_style</span></a> command) with ID = <em>thermo_temp</em>.
This means you can change the attributes of this fix’s temperature
(e.g. its degrees-of-freedom) via the
<aclass="reference internal"href="compute_modify.html"><spanclass="doc">compute_modify</span></a> command or print this temperature
during thermodynamic output via the <aclass="reference internal"href="thermo_style.html"><spanclass="doc">thermo_style custom</span></a> command using the appropriate compute-ID.
It also means that changing attributes of <em>thermo_temp</em> will have no
effect on this fix.</p>
<p>Like other fixes that perform thermostatting, this fix can be used
with <aclass="reference internal"href="compute.html"><spanclass="doc">compute commands</span></a> that calculate a temperature
after removing a “bias” from the atom velocities. E.g. removing the
center-of-mass velocity from a group of atoms or only calculating
temperature on the x-component of velocity or only calculating
temperature for atoms in a geometric region. This is not done by
default, but only if the <aclass="reference internal"href="fix_modify.html"><spanclass="doc">fix_modify</span></a> command is used
to assign a temperature compute to this fix that includes such a bias
term. See the doc pages for individual <aclass="reference internal"href="compute.html"><spanclass="doc">compute commands</span></a> to determine which ones include a bias. In
this case, the thermostat works in the following manner: the current
temperature is calculated taking the bias into account, bias is
removed from each atom, thermostatting is performed on the remaining
thermal degrees of freedom, and the bias is added back in.</p>
<hrclass="docutils"/>
<p>Styles with a <em>cuda</em>, <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in <aclass="reference internal"href="Section_accelerate.html"><spanclass="doc">Section_accelerate</span></a>
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.</p>
<p>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
KOKKOS, USER-OMP and OPT packages, respectively. They are only
enabled if LAMMPS was built with those packages. See the <aclass="reference internal"href="Section_start.html#start-3"><spanclass="std std-ref">Making LAMMPS</span></a> section for more info.</p>
<p>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <aclass="reference internal"href="Section_start.html#start-7"><spanclass="std std-ref">-suffix command-line switch</span></a> when you invoke LAMMPS, or you can
use the <aclass="reference internal"href="suffix.html"><spanclass="doc">suffix</span></a> command in your input script.</p>
<p>See <aclass="reference internal"href="Section_accelerate.html"><spanclass="doc">Section_accelerate</span></a> of the manual for
more instructions on how to use the accelerated styles effectively.</p>
<h2>Restart, fix_modify, output, run start/stop, minimize info</h2>
<p>This fix writes the state of the Nose/Hoover thermostat to <aclass="reference internal"href="restart.html"><spanclass="doc">binary restart files</span></a>. See the <aclass="reference internal"href="read_restart.html"><spanclass="doc">read_restart</span></a>
command for info on how to re-specify a fix in an input script that
reads a restart file, so that the operation of the fix continues in an
uninterrupted fashion.</p>
<p>The <aclass="reference internal"href="fix_modify.html"><spanclass="doc">fix_modify</span></a><em>temp</em> option is supported by this
fix. You can use it to assign a <aclass="reference internal"href="compute.html"><spanclass="doc">compute</span></a> you have
defined to this fix which will be used in its thermostatting
procedure.</p>
<p>The <aclass="reference internal"href="fix_modify.html"><spanclass="doc">fix_modify</span></a><em>energy</em> option is supported by this
fix to add the energy change induced by Nose/Hoover thermostatting to
the system’s potential energy as part of <aclass="reference internal"href="thermo_style.html"><spanclass="doc">thermodynamic output</span></a>.</p>
<p>This fix computes the same global scalar and global vector of
quantities as does the <aclass="reference internal"href="fix_nh.html"><spanclass="doc">fix nvt</span></a> command.</p>
<p>This fix can ramp its target temperature over multiple runs, using the
<em>start</em> and <em>stop</em> keywords of the <aclass="reference internal"href="run.html"><spanclass="doc">run</span></a> command. See the
<aclass="reference internal"href="run.html"><spanclass="doc">run</span></a> command for details of how to do this.</p>
<p>This fix is not invoked during <aclass="reference internal"href="minimize.html"><spanclass="doc">energy minimization</span></a>.</p>
</div>
<divclass="section"id="restrictions">
<h2>Restrictions</h2>
<p>This fix works best without Nose-Hoover chain thermostats, i.e. using
tchain = 1. Setting tchain to larger values can result in poor
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