2010-08-09 22:09:03 +08:00
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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>pair_style peri/pmb command
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</H3>
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2011-10-07 01:32:51 +08:00
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<H3>pair_style peri/pmb/omp command
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</H3>
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2010-08-09 22:09:03 +08:00
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<H3>pair_style peri/lps command
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</H3>
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2011-10-07 01:32:51 +08:00
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<H3>pair_style peri/lps/omp command
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</H3>
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2013-07-27 00:57:44 +08:00
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<H3>pair_style peri/ves command
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</H3>
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2010-08-09 22:09:03 +08:00
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style style
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</PRE>
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2013-07-27 00:57:44 +08:00
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<UL><LI>style = <I>peri/pmb</I> or <I>peri/lps</I> or <I>peri/ves</I>
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2010-08-09 22:09:03 +08:00
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>pair_style peri/pmb
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pair_coeff * * 1.6863e22 0.0015001 0.0005 0.25
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</PRE>
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<PRE>pair_style peri/lps
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pair_coeff * * 14.9e9 14.9e9 0.0015001 0.0005 0.25
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</PRE>
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2013-07-27 00:57:44 +08:00
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<PRE>pair_style peri/ves
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pair_coeff * * 14.9e9 14.9e9 0.0015001 0.0005 0.25 0.5 0.001
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</PRE>
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2010-08-09 22:09:03 +08:00
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<P><B>Description:</B>
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</P>
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<P>The peridynamic pair styles implement material models that can be used
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at the mescscopic and macroscopic scales.
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</P>
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<P>Style <I>peri/pmb</I> implements the Peridynamic bond-based prototype
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microelastic brittle (PMB) model.
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</P>
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<P>Style <I>peri/lps</I> implements the Peridynamic state-based linear
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peridynamic solid (LPS) model.
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</P>
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2013-07-27 00:57:44 +08:00
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<P>Style <I>peri/ves</I> implements the Peridynamic state-based linear
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peridynamic viscoelastic solid (VES) model.
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</P>
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2010-08-09 22:09:03 +08:00
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<P>The canonical papers on Peridynamics are <A HREF = "#Silling2000">(Silling 2000)</A>
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and <A HREF = "#Silling2007">(Silling 2007)</A>. The implementation of Peridynamics
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in LAMMPS is described in <A HREF = "#Parks">(Parks)</A>. Also see the <A HREF = "http://www.sandia.gov/~mlparks/papers/PDLAMMPS.pdf">PDLAMMPS
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user guide</A> for
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more details about the implementation of peridynamics in LAMMPS.
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</P>
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2013-07-27 00:57:44 +08:00
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<P>The peridynamic VES model in PDLAMMPS is implemented by R. Rahman and
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J.T Foster at University of Texas at San Antonio. The VES formulation
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is described in "(Mtchell2011)". For question regarding VES
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implementation in LAMMPS please contact R.Rahman:
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rezwanur.rahman@utsa.edu
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</P>
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2010-08-09 22:09:03 +08:00
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<P>The following coefficients must be defined for each pair of atom types
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via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples above,
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or in the data file or restart files read by the
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<A HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</A>
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commands, or by mixing as described below.
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</P>
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<P>For the <I>peri/pmb</I> style:
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</P>
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<UL><LI>c (energy/distance/volume^2 units)
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<LI>horizon (distance units)
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<LI>s00 (unitless)
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<LI>alpha (unitless)
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</UL>
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<P>C is the effectively a spring constant for Peridynamic bonds, the
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horizon is a cutoff distance for truncating interactions, and s00 and
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alpha are used as a bond breaking criteria. The units of c are such
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that c/distance = stiffness/volume^2, where stiffness is
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energy/distance^2 and volume is distance^3. See the users guide for
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more details.
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</P>
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<P>For the <I>peri/lps</I> style:
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</P>
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<UL><LI>K (force/area units)
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<LI>G (force/area units)
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<LI>horizon (distance units)
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<LI>s00 (unitless)
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<LI>alpha (unitless)
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</UL>
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<P>K is the bulk modulus and G is the shear modulus. The horizon is a
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cutoff distance for truncating interactions, and s00 and alpha are
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used as a bond breaking criteria. See the users guide for more
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details.
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</P>
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2013-07-27 00:57:44 +08:00
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<P>For the <I>peri/ves</I> style:
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</P>
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<UL><LI>K (force/area units)
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<LI>G (force/area units)
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<LI>horizon (distance units)
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<LI>s00 (unitless)
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<LI>alpha (unitless)
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<LI>m_lambdai (unitless)
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<LI>m_taubi (unitless)
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</UL>
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<P>The same as for <I>peri/lps</I>, K is the bulk modulus and G is the shear
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modulus. The horizon is a cutoff distance for truncating interactions,
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and s00 and alpha are used as a bond breaking criteria. m_lambdai and
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m_taubi are the viscoelastic relaxation parameter and time constant,
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respectively. m_lambdai varies within zero to one. For very small
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values of m_lambdai the viscoelsatic model responds very similar to a
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linear elastic model. For details see the description in
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<A HREF = "#Mitchell">(Mitchell)</A>.
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</P>
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2010-08-09 22:09:03 +08:00
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<HR>
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2011-12-14 04:35:35 +08:00
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<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>omp</I>, or <I>opt</I> suffix are functionally
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the same as the corresponding style without the suffix. They have
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been optimized to run faster, depending on your available hardware, as
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discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A> of the
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manual. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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2011-10-07 01:32:51 +08:00
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</P>
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<P>These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
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packages, respectively. They are only enabled if LAMMPS was built with
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those packages. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A>
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section for more info.
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</P>
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<P>You can specify the accelerated styles explicitly in your input script
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2012-01-28 07:39:14 +08:00
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by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
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2011-10-07 01:32:51 +08:00
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switch</A> when you invoke LAMMPS, or you can
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use the <A HREF = "suffix.html">suffix</A> command in your input script.
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</P>
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2011-12-14 04:35:35 +08:00
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<P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
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more instructions on how to use the accelerated styles effectively.
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2011-10-07 01:32:51 +08:00
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</P>
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<HR>
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2010-08-09 22:09:03 +08:00
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<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
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</P>
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<P>These pair styles do not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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</P>
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<P>These pair styles do not support the <A HREF = "pair_modify.html">pair_modify</A>
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shift option.
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</P>
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<P>The <A HREF = "pair_modify.html">pair_modify</A> table and tail options are not
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relevant for these pair styles.
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</P>
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<P>These pair styles write their information to <A HREF = "restart.html">binary restart
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files</A>, so pair_style and pair_coeff commands do not need
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to be specified in an input script that reads a restart file.
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</P>
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<P>These pair styles can only be used via the <I>pair</I> keyword of the
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<A HREF = "run_style.html">run_style respa</A> command. They do not support the
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<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
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</P>
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<HR>
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<P><B>Restrictions:</B>
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</P>
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2013-07-27 00:57:44 +08:00
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<P>The <I>peri/pmb</I>, <I>peri/lps</I> and <I>peri/ves</I> styles are part of the PERI
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2010-08-09 22:09:03 +08:00
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package. They are only enabled if LAMMPS was built with that package.
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2011-08-26 00:46:23 +08:00
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See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> section for more
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info.
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2010-08-09 22:09:03 +08:00
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "pair_coeff.html">pair_coeff</A>
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</P>
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<P><B>Default:</B> none
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</P>
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<HR>
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<A NAME = "Parks"></A>
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2013-07-27 00:57:44 +08:00
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<P><B>(Parks)</B> Parks, Lehoucq, Plimpton, Silling, Comp Phys Comm, 179(11),
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777-783 (2008).
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2010-08-09 22:09:03 +08:00
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</P>
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<A NAME = "Silling2000"></A>
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<P><B>(Silling 2000)</B> Silling, J Mech Phys Solids, 48, 175-209 (2000).
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</P>
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<A NAME = "Silling2007"></A>
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2013-07-27 00:57:44 +08:00
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<P><B>(Silling 2007)</B> Silling, Epton, Weckner, Xu, Askari, J Elasticity,
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88, 151-184 (2007).
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</P>
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<A NAME = "Mitchell"></A>
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<P><B>(Mitchell)</B> Mitchell, "A non-local, ordinary-state-based
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viscoelasticity model for peridynamics", Sandia National Lab Report,
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8064:1-28 (2011).
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2010-08-09 22:09:03 +08:00
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</P>
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</HTML>
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