2013-09-17 07:02:40 +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 zbl command
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</H3>
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2013-10-30 23:41:56 +08:00
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<H3>pair_style zbl/omp command
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</H3>
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2013-09-17 07:02:40 +08:00
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style zbl inner outer
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</PRE>
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<UL><LI>inner = distance where switching function begins
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<LI>outer = global cutoff for ZBL interaction
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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 zbl 3.0 4.0
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pair_coeff * * 73.0
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pair_coeff 1 1 14.0
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</PRE>
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<P><B>Description:</B>
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</P>
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2013-09-18 03:08:43 +08:00
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<P>Style <I>zbl</I> computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
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repulsion for describing high-energy collisions between atoms.
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<A HREF = "#Ziegler">(Ziegler)</A>. It includes an additional switching function
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that ramps the energy, force, and curvature smoothly to zero
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between an inner and outer cutoff. The potential
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energy due to a pair of atoms at a distance r_ij is given by:
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</P>
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<CENTER><IMG SRC = "Eqs/pair_zbl.jpg">
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</CENTER>
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2014-03-18 22:59:36 +08:00
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<P>where e is the electron charge, epsilon_0 is the electrical
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permittivity of vacuum, and Z_i and Z_j are the nuclear charges of the
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two atoms. The switching function S(r) is identical to that used by
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<A HREF = "pair_gromacs.html">pair_style lj/gromacs</A>. Here, the inner and outer
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cutoff are the same for all pairs of atom types.
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</P>
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<P>The following coefficient 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 LAMMPS data file. Z can not be specified for two different
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atoms types. Therefore the lists of atom types I and atom types J
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must match.
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</P>
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<UL><LI>Z (multiples of proton charge, e.g. 13.0 for aluminum)
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</UL>
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<P>Although Z must be defined for all atom type pairs I,J, it is only
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stored for individual atom types, i.e. when I = J. Z is normally equal
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to the atomic number of the atom type.
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</P>
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<P>IMPORTANT NOTE: The numerical values of the exponential decay
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constants in the screening function depend on the unit of distance. In
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the above equation they are given for units of angstroms. LAMMPS will
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automatically convert these values to the distance unit of the
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specified LAMMPS <A HREF = "units.html">units</A> setting. The values of Z should
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always be given as multiples of a proton's charge, e.g. 29.0 for
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copper.
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2013-09-17 07:02:40 +08:00
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</P>
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<HR>
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2013-10-30 23:41:56 +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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</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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by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
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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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<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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</P>
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<HR>
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2013-09-17 07:02:40 +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>Mixing is not relevant for this pair style, since as explained above,
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Z values are stored on a per-type basis, and both Zi and Zj are used
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explicitly in the ZBL formula.
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</P>
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2013-09-18 03:50:20 +08:00
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<P>The ZBL pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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shift option, since the ZBL interaction is already smoothed to 0.0 at
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the cutoff.
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</P>
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2013-09-18 03:50:20 +08:00
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<P>The <A HREF = "pair_modify.html">pair_modify</A> table option is not relevant for
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this pair style.
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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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tail option for adding long-range tail corrections to energy and
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pressure, since there are no corrections for a potential that goes to
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0.0 at the cutoff.
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</P>
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<P>This pair style does not write information to <A HREF = "restart.html">binary restart
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files</A>, so pair_style and pair_coeff commands must be
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specified in an input script that reads a restart file.
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</P>
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<P>This 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. It does not support the
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<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
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2013-09-17 07:02:40 +08:00
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</P>
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<HR>
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<P><B>Restrictions:</B> none
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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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2013-09-18 03:08:43 +08:00
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<A NAME = "Ziegler"></A>
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2013-09-17 07:02:40 +08:00
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2013-09-18 03:08:43 +08:00
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<P><B>(Ziegler)</B> J.F. Ziegler, J. P. Biersack and U. Littmark, "The
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Stopping and Range of Ions in Matter," Volume 1, Pergamon, 1985.
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</P>
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</HTML>
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