<spanid="index-0"></span><h1>fix smd/adjust_dt command<aclass="headerlink"href="#fix-smd-adjust-dt-command"title="Permalink to this headline">¶</a></h1>
<divclass="section"id="syntax">
<h2>Syntax<aclass="headerlink"href="#syntax"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>fix ID group-ID smd/adjust_dt arg
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<ulclass="simple">
<li>ID, group-ID are documented in <aclass="reference internal"href="fix.html"><em>fix</em></a> command</li>
<li>smd/adjust_dt = style name of this fix command</li>
<li>arg = <em>s_fact</em></li>
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<preclass="literal-block">
<em>s_fact</em> = safety factor
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<divclass="section"id="examples">
<h2>Examples<aclass="headerlink"href="#examples"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>fix 1 all smd/adjust_dt 0.1
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<divclass="section"id="description">
<h2>Description<aclass="headerlink"href="#description"title="Permalink to this headline">¶</a></h2>
<p>The fix calculates a new stable time increment for use with the SMD time integrators.</p>
<p>The stable time increment is based on multiple conditions. For the SPH pair styles, a
CFL criterion (Courant, Friedrichs & Lewy, 1928) is evaluated, which determines the the speed of
sound cannot propagate further than a typical spacing between particles within a single time step to ensure
no information is lost. For the contact pair styles, a linear analysis of the pair potential determines a
stable maximum time step.</p>
<p>This fix inquires the minimum stable time increment across all particles contained in the group for which this
fix is defined. An additional safety factor <em>s_fact</em> is applied to the time increment.</p>
<p>See <aclass="reference external"href="USER/smd/SMD_LAMMPS_userguide.pdf">this PDF guide</a> to use Smooth Mach Dynamics in LAMMPS.</p>
<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>Currently, no part of USER-SMD supports restarting nor minimization.</p>
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<divclass="section"id="restrictions">
<h2>Restrictions<aclass="headerlink"href="#restrictions"title="Permalink to this headline">¶</a></h2>
<p>This fix is part of the USER-SMD package. It is only enabled if
LAMMPS was built with that package. See the <aclass="reference internal"href="Section_start.html#start-3"><span>Making LAMMPS</span></a>
section for more info.</p>
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<divclass="section"id="related-commands">
<h2>Related commands<aclass="headerlink"href="#related-commands"title="Permalink to this headline">¶</a></h2>
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