forked from lijiext/lammps
97 lines
3.3 KiB
HTML
97 lines
3.3 KiB
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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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<HR>
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<H3>pair_style meam/spline
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style meam/spline
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</PRE>
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<P><B>Examples:</B>
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</P>
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<PRE>pair_style meam/spline
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pair_coeff * * Ti.splinemeam
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>The <I>meam/spline</I> style computes pairwise interactions for metals
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using a variant of modified embedded-atom method (MEAM) potentials <A HREF = "#Lenosky">(Lenosky)</A>. The total
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energy E is given by
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</P>
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<CENTER><IMG SRC = "spline_meam_formula1.png">
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</CENTER>
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<P>with the density at atom i
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</P>
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<CENTER><IMG SRC = "spline_meam_formula2.png">
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</CENTER>
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<P>where theta_jik is the angle between atoms j, i, and k centered on
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atom i. The five functions Phi, U, rho, f, and g are represented by cubic
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splines.
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</P>
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<P>The cutoffs and the coefficients for these spline functions are listed
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in a parameter file which is specified by the <A HREF = "pair_coeff.html">pair_coeff</A> command.
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Parameter files for different elements are
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included in the "potentials" directory of the LAMMPS distribution and have a ".splinemeam" file suffix.
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All of these files are parameterized in terms of LAMMPS <A HREF = "units.html">metal units</A>.
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</P>
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<P>IMPORTANT NOTE: The <I>meam/spline</I> style currently supports only single-element MEAM potentials.
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</P>
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<P>The cutoff for spline-based MEAM potentials is
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not set in the pair_style or pair_coeff command; it is specified in
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the potential parameter file.
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</P>
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<P>Unlike the EAM pair style, which retrieves the atomic mass from the potential file,
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the spline-based MEAM potentials do not include mass information; thus you need to use the <A HREF = "mass.html">mass</A>
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command to specify it.
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</P>
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<HR>
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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>The current version of this pair style does not support multiple element types or mixing.
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It has been designed for pure elements only.
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</P>
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<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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shift, table, and tail options.
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</P>
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<P>The <I>meam/spline</I> pair style does not write its information to <A HREF = "restart.html">binary restart
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files</A>, since it is stored in an external potential parameter file.
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Thus, you need to re-specify the pair_style and pair_coeff commands in
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an input script that reads a restart file.
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</P>
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<P>The <I>meam/spline</I> pair style 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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<P>This pair style requires the <A HREF = "newton.html">newton</A> setting to be "on"
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for pair interactions.
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</P>
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<P>This pair style is only enabled if LAMMPS was built with the USER-MISC package.
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See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> section for more info.
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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 = "Lenosky"></A>
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<P><B>(Lenosky)</B> Lenosky, Sadigh, Alonso, Bulatov, de la Rubia, Kim, Voter, Kress, Modell. Simul. Mater. Sci. Eng. 8, 825 (2000).
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</P>
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</HTML>
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