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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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<H3>fix smd/adjust_dt command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>fix ID group-ID smd/adjust_dt arg
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
<LI>smd/adjust_dt = style name of this fix command
<LI>arg = <I>s_fact</I>
<PRE> <I>s_fact</I> = safety factor
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix 1 all smd/adjust_dt 0.1
</PRE>
<P><B>Description:</B>
</P>
<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 <I>s_fact</I> is applied to the time increment.
</P>
<P>See <A HREF = "USER/smd/SMD_LAMMPS_userguide.pdf">this PDF guide</A> to use Smooth Mach Dynamics in LAMMPS.
</P>
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
</P>
<P>Currently, no part of USER-SMD supports restarting nor minimization.
</P>
<P><B>Restrictions:</B>
</P>
<P>This fix is part of the USER-SMD package. It is only enabled if
LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A>
section for more info.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "compute_smd_tlsph_dt.html">smd/tlsph_dt</A>
</P>
<P><B>Default:</B> none
</P>
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