<h2>Description<aclass="headerlink"href="#description"title="Permalink to this headline">¶</a></h2>
<p>Perform updates of position and velocity for atoms in the group each
timestep using the specified settings or formulas, without regard to
forces on the atoms. This can be useful for boundary or other atoms,
whose movement can influence nearby atoms.</p>
<divclass="admonition note">
<pclass="first admonition-title">Note</p>
<pclass="last">The atoms affected by this fix should not normally be time
integrated by other fixes (e.g. <aclass="reference internal"href="fix_nve.html"><em>fix nve</em></a>, <aclass="reference internal"href="fix_nh.html"><em>fix nvt</em></a>), since that will change their positions and
velocities twice.</p>
</div>
<divclass="admonition note">
<pclass="first admonition-title">Note</p>
<pclass="last">As atoms move due to this fix, they will pass thru periodic
boundaries and be remapped to the other side of the simulation box,
just as they would during normal time integration (e.g. via the <aclass="reference internal"href="fix_nve.html"><em>fix nve</em></a> command). It is up to you to decide whether
periodic boundaries are appropriate with the kind of atom motion you
are prescribing with this fix.</p>
</div>
<divclass="admonition note">
<pclass="first admonition-title">Note</p>
<pclass="last">As dicsussed below, atoms are moved relative to their initial
position at the time the fix is specified. These initial coordinates
are stored by the fix in “unwrapped” form, by using the image flags
associated with each atom. See the <aclass="reference internal"href="dump.html"><em>dump custom</em></a> command
for a discussion of “unwrapped” coordinates. See the Atoms section of
the <aclass="reference internal"href="read_data.html"><em>read_data</em></a> command for a discussion of image flags
and how they are set for each atom. You can reset the image flags
(e.g. to 0) before invoking this fix by using the <aclass="reference internal"href="set.html"><em>set image</em></a>
command.</p>
</div>
<hrclass="docutils"/>
<p>The <em>linear</em> style moves atoms at a constant velocity, so that their
position <em>X</em> = (x,y,z) as a function of time is given in vector
<h2>Restart, fix_modify, output, run start/stop, minimize info<aclass="headerlink"href="#restart-fix-modify-output-run-start-stop-minimize-info"title="Permalink to this headline">¶</a></h2>
<p>This fix writes the original coordinates of moving atoms to <aclass="reference internal"href="restart.html"><em>binary restart files</em></a>, as well as the initial timestep, so that
the motion can be continuous in a restarted simulation. See the
<aclass="reference internal"href="read_restart.html"><em>read_restart</em></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>IMPORTANNT NOTE: Because the move positions are a function of the
current timestep and the initial timestep, you cannot reset the
timestep to a different value after reading a restart file, if you
expect a fix move command to work in an uninterrupted fashion.</p>
<p>None of the <aclass="reference internal"href="fix_modify.html"><em>fix_modify</em></a> options are relevant to this
fix.</p>
<p>This fix produces a per-atom array which can be accessed by various
<aclass="reference internal"href="Section_howto.html#howto-15"><span>output commands</span></a>. The number of columns
for each atom is 3, and the columns store the original unwrapped x,y,z
coords of each atom. The per-atom values can be accessed on any
timestep.</p>
<p>No parameter of this fix can be used with the <em>start/stop</em> keywords of
the <aclass="reference internal"href="run.html"><em>run</em></a> command. This fix is not invoked during <aclass="reference internal"href="minimize.html"><em>energy minimization</em></a>.</p>
<p>For <aclass="reference internal"href="run_style.html"><em>rRESPA time integration</em></a>, this fix adjusts the
position and velocity of atoms on the outermost rRESPA level.</p>
</div>
<divclass="section"id="restrictions">
<h2>Restrictions<aclass="headerlink"href="#restrictions"title="Permalink to this headline">¶</a></h2>
<blockquote>
<div>none</div></blockquote>
</div>
<divclass="section"id="related-commands">
<h2>Related commands<aclass="headerlink"href="#related-commands"title="Permalink to this headline">¶</a></h2>
Built with <ahref="http://sphinx-doc.org/">Sphinx</a> using a <ahref="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <ahref="https://readthedocs.org">Read the Docs</a>.