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Modifed ZBL to accomodate mixing 

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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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<title>pair_style zbl command &mdash; LAMMPS 15 May 2015 version documentation</title>
<HR>
<H3>pair_style zbl command
</H3>
<H3>pair_style zbl/gpu command
</H3>
<H3>pair_style zbl/omp command
</H3>
<P><B>Syntax:</B>
</P>
<link rel="stylesheet" href="_static/css/theme.css" type="text/css" /> <PRE>pair_style zbl inner outer
</PRE>
<UL><LI>inner = distance where switching function begins
<LI>outer = global cutoff for ZBL interaction
<link rel="stylesheet" href="_static/sphinxcontrib-images/LightBox2/lightbox2/css/lightbox.css" type="text/css" /> </UL>
<P><B>Examples:</B>
</P>
<PRE>pair_style zbl 3.0 4.0
<link rel="top" title="LAMMPS 15 May 2015 version documentation" href="index.html"/> pair_coeff * * 73.0 73.0
pair_coeff 1 1 14.0 14.0
</PRE>
<script src="_static/js/modernizr.min.js"></script> <P><B>Description:</B>
</P>
</head> <P>Style <I>zbl</I> computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
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<li class="toctree-l1"><a class="reference internal" href="Section_intro.html">1. Introduction</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_start.html">2. Getting Started</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_python.html">11. Python interface to LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_errors.html">12. Errors</a></li>
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<div class="section" id="pair-style-zbl-command">
<span id="index-0"></span><h1>pair_style zbl command<a class="headerlink" href="#pair-style-zbl-command" title="Permalink to this headline"></a></h1>
</div>
<div class="section" id="pair-style-zbl-gpu-command">
<h1>pair_style zbl/gpu command<a class="headerlink" href="#pair-style-zbl-gpu-command" title="Permalink to this headline"></a></h1>
</div>
<div class="section" id="pair-style-zbl-omp-command">
<h1>pair_style zbl/omp command<a class="headerlink" href="#pair-style-zbl-omp-command" title="Permalink to this headline"></a></h1>
<div class="section" id="syntax">
<h2>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline"></a></h2>
<div class="highlight-python"><div class="highlight"><pre>pair_style zbl inner outer
</pre></div>
</div>
<ul class="simple">
<li>inner = distance where switching function begins</li>
<li>outer = global cutoff for ZBL interaction</li>
</ul>
</div>
<div class="section" id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline"></a></h2>
<div class="highlight-python"><div class="highlight"><pre>pair_style zbl 3.0 4.0
pair_coeff * * 73.0
pair_coeff 1 1 14.0
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
<p>Style <em>zbl</em> computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
repulsion for describing high-energy collisions between atoms. repulsion for describing high-energy collisions between atoms.
<a class="reference internal" href="#ziegler"><span>(Ziegler)</span></a>. It includes an additional switching function <A HREF = "#Ziegler">(Ziegler)</A>. It includes an additional switching function
that ramps the energy, force, and curvature smoothly to zero that ramps the energy, force, and curvature smoothly to zero
between an inner and outer cutoff. The potential between an inner and outer cutoff. The potential
energy due to a pair of atoms at a distance r_ij is given by:</p> energy due to a pair of atoms at a distance r_ij is given by:
<img alt="_images/pair_zbl.jpg" class="align-center" src="_images/pair_zbl.jpg" /> </P>
<p>where e is the electron charge, epsilon_0 is the electrical <CENTER><IMG SRC = "Eqs/pair_zbl.jpg">
</CENTER>
<P>where e is the electron charge, epsilon_0 is the electrical
permittivity of vacuum, and Z_i and Z_j are the nuclear charges of the permittivity of vacuum, and Z_i and Z_j are the nuclear charges of the
two atoms. The switching function S(r) is identical to that used by two atoms. The switching function S(r) is identical to that used by
<a class="reference internal" href="pair_gromacs.html"><em>pair_style lj/gromacs</em></a>. Here, the inner and outer <A HREF = "pair_gromacs.html">pair_style lj/gromacs</A>. Here, the inner and outer
cutoff are the same for all pairs of atom types.</p> cutoff are the same for all pairs of atom types.
<p>The following coefficient must be defined for each pair of atom types </P>
via the <a class="reference internal" href="pair_coeff.html"><em>pair_coeff</em></a> command as in the examples above, <P>The following coefficients must be defined for each pair of atom types
or in the LAMMPS data file. Z can not be specified for two different via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples above,
atoms types. Therefore the lists of atom types I and atom types J or in the LAMMPS data file.
must match.</p> </P>
<ul class="simple"> <UL><LI>Z_i (atomic number for first atom type, e.g. 13.0 for aluminum)
<li>Z (multiples of proton charge, e.g. 13.0 for aluminum)</li> </UL>
</ul> <UL><LI>Z_j (ditto for second atom type)
<p>Although Z must be defined for all atom type pairs I,J, it is only </UL>
stored for individual atom types, i.e. when I = J. Z is normally equal <P>The values of Z_i and Z_j are normally equal to the atomic
to the atomic number of the atom type.</p> numbers of the two atom types. Thus, the user may optionally
<div class="admonition warning"> specify only the coefficients for each I==I pair, and rely
<p class="first admonition-title">Warning</p> on the obvious mixing rule for cross interactions (see below).
<p class="last">The numerical values of the exponential decay Note that when I==I it is required that Z_i == Z_j. When used
with <A HREF = "pair_hybrid.html">hybrid/overlay</A> and pairs are assigned
to more than one sub-style, the mixing rule is not used and
each pair of types interacting with the ZBL sub-style must
be included in a pair_coeff command.
</P>
<P>IMPORTANT NOTE: The numerical values of the exponential decay
constants in the screening function depend on the unit of distance. In constants in the screening function depend on the unit of distance. In
the above equation they are given for units of angstroms. LAMMPS will the above equation they are given for units of angstroms. LAMMPS will
automatically convert these values to the distance unit of the automatically convert these values to the distance unit of the
specified LAMMPS <a class="reference internal" href="units.html"><em>units</em></a> setting. The values of Z should specified LAMMPS <A HREF = "units.html">units</A> setting. The values of Z should
always be given as multiples of a proton&#8217;s charge, e.g. 29.0 for always be given as multiples of a proton's charge, e.g. 29.0 for
copper.</p> copper.
</div> </P>
<hr class="docutils" /> <HR>
<p>Styles with a <em>cuda</em>, <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> suffix are
<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>intel</I>, <I>kk</I>, <I>omp</I>, or <I>opt</I> suffix are
functionally the same as the corresponding style without the suffix. functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available They have been optimized to run faster, depending on your available
hardware, as discussed in <a class="reference internal" href="Section_accelerate.html"><em>Section_accelerate</em></a> hardware, as discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A>
of the manual. The accelerated styles take the same arguments and of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision should produce the same results, except for round-off and precision
issues.</p> issues.
<p>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL, </P>
<P>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
KOKKOS, USER-OMP and OPT packages, respectively. They are only KOKKOS, USER-OMP and OPT packages, respectively. They are only
enabled if LAMMPS was built with those packages. See the <a class="reference internal" href="Section_start.html#start-3"><span>Making LAMMPS</span></a> section for more info.</p> enabled if LAMMPS was built with those packages. See the <A HREF = "Section_start.html#start_3">Making
<p>You can specify the accelerated styles explicitly in your input script LAMMPS</A> section for more info.
by including their suffix, or you can use the <a class="reference internal" href="Section_start.html#start-7"><span>-suffix command-line switch</span></a> when you invoke LAMMPS, or you can </P>
use the <a class="reference internal" href="suffix.html"><em>suffix</em></a> command in your input script.</p> <P>You can specify the accelerated styles explicitly in your input script
<p>See <a class="reference internal" href="Section_accelerate.html"><em>Section_accelerate</em></a> of the manual for by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
more instructions on how to use the accelerated styles effectively.</p> switch</A> when you invoke LAMMPS, or you can
<hr class="docutils" /> use the <A HREF = "suffix.html">suffix</A> command in your input script.
<p><strong>Mixing, shift, table, tail correction, restart, rRESPA info</strong>:</p> </P>
<p>Mixing is not relevant for this pair style, since as explained above, <P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
Z values are stored on a per-type basis, and both Zi and Zj are used more instructions on how to use the accelerated styles effectively.
explicitly in the ZBL formula.</p> </P>
<p>The ZBL pair style does not support the <a class="reference internal" href="pair_modify.html"><em>pair_modify</em></a> <HR>
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
</P>
<P>For atom type pairs I,J and I != J, the Z_i and Z_j coefficients
can be mixed by taking Z_i and Z_j from the values specified for
I == I and J == J cases. When used
with <A HREF = "pair_hybrid.html">hybrid/overlay</A> and pairs are assigned
to more than one sub-style, the mixing rule is not used and
each pair of types interacting with the ZBL sub-style
must be included in a pair_coeff command.
The <A HREF = "pair_modify.html">pair_modify</A> mix option has no effect on
the mixing behavior
</P>
<P>The ZBL pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
shift option, since the ZBL interaction is already smoothed to 0.0 at shift option, since the ZBL interaction is already smoothed to 0.0 at
the cutoff.</p> the cutoff.
<p>The <a class="reference internal" href="pair_modify.html"><em>pair_modify</em></a> table option is not relevant for </P>
this pair style.</p> <P>The <A HREF = "pair_modify.html">pair_modify</A> table option is not relevant for
<p>This pair style does not support the <a class="reference internal" href="pair_modify.html"><em>pair_modify</em></a> this pair style.
</P>
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
tail option for adding long-range tail corrections to energy and tail option for adding long-range tail corrections to energy and
pressure, since there are no corrections for a potential that goes to pressure, since there are no corrections for a potential that goes to
0.0 at the cutoff.</p> 0.0 at the cutoff.
<p>This pair style does not write information to <a class="reference internal" href="restart.html"><em>binary restart files</em></a>, so pair_style and pair_coeff commands must be </P>
specified in an input script that reads a restart file.</p> <P>This pair style does not write information to <A HREF = "restart.html">binary restart
<p>This pair style can only be used via the <em>pair</em> keyword of the files</A>, so pair_style and pair_coeff commands must be
<a class="reference internal" href="run_style.html"><em>run_style respa</em></a> command. It does not support the specified in an input script that reads a restart file.
<em>inner</em>, <em>middle</em>, <em>outer</em> keywords.</p> </P>
</div> <P>This pair style can only be used via the <I>pair</I> keyword of the
<hr class="docutils" /> <A HREF = "run_style.html">run_style respa</A> command. It does not support the
<div class="section" id="restrictions"> <I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Permalink to this headline"></a></h2> </P>
<blockquote> <HR>
<div>none</div></blockquote>
</div>
<div class="section" id="related-commands">
<h2>Related commands<a class="headerlink" href="#related-commands" title="Permalink to this headline"></a></h2>
<p><a class="reference internal" href="pair_coeff.html"><em>pair_coeff</em></a></p>
<p><strong>Default:</strong> none</p>
<hr class="docutils" />
<p id="ziegler"><strong>(Ziegler)</strong> J.F. Ziegler, J. P. Biersack and U. Littmark, &#8220;The
Stopping and Range of Ions in Matter,&#8221; Volume 1, Pergamon, 1985.</p>
</div>
</div>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "pair_coeff.html">pair_coeff</A>
</P>
<P><B>Default:</B> none
</P>
<HR>
</div> <A NAME = "Ziegler"></A>
</div>
<footer>
<P><B>(Ziegler)</B> J.F. Ziegler, J. P. Biersack and U. Littmark, "The
<hr/> Stopping and Range of Ions in Matter," Volume 1, Pergamon, 1985.
</P>
<div role="contentinfo"> </HTML>
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37
doc/pair_zbl.txt
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@ -20,8 +20,8 @@ outer = global cutoff for ZBL interaction :ul
[Examples:] [Examples:]
pair_style zbl 3.0 4.0 pair_style zbl 3.0 4.0
pair_coeff * * 73.0 pair_coeff * * 73.0 73.0
pair_coeff 1 1 14.0 :pre pair_coeff 1 1 14.0 14.0 :pre
[Description:] [Description:]
@ -40,17 +40,22 @@ two atoms. The switching function S(r) is identical to that used by
"pair_style lj/gromacs"_pair_gromacs.html. Here, the inner and outer "pair_style lj/gromacs"_pair_gromacs.html. Here, the inner and outer
cutoff are the same for all pairs of atom types. cutoff are the same for all pairs of atom types.
The following coefficient must be defined for each pair of atom types The following coefficients must be defined for each pair of atom types
via the "pair_coeff"_pair_coeff.html command as in the examples above, via the "pair_coeff"_pair_coeff.html command as in the examples above,
or in the LAMMPS data file. Z can not be specified for two different or in the LAMMPS data file.
atoms types. Therefore the lists of atom types I and atom types J
must match.
Z (multiples of proton charge, e.g. 13.0 for aluminum) :ul Z_i (atomic number for first atom type, e.g. 13.0 for aluminum) :ul
Z_j (ditto for second atom type) :ul
Although Z must be defined for all atom type pairs I,J, it is only The values of Z_i and Z_j are normally equal to the atomic
stored for individual atom types, i.e. when I = J. Z is normally equal numbers of the two atom types. Thus, the user may optionally
to the atomic number of the atom type. specify only the coefficients for each I==I pair, and rely
on the obvious mixing rule for cross interactions (see below).
Note that when I==I it is required that Z_i == Z_j. When used
with "hybrid/overlay"_pair_hybrid.html and pairs are assigned
to more than one sub-style, the mixing rule is not used and
each pair of types interacting with the ZBL sub-style must
be included in a pair_coeff command.
IMPORTANT NOTE: The numerical values of the exponential decay IMPORTANT NOTE: The numerical values of the exponential decay
constants in the screening function depend on the unit of distance. In constants in the screening function depend on the unit of distance. In
@ -87,9 +92,15 @@ more instructions on how to use the accelerated styles effectively.
[Mixing, shift, table, tail correction, restart, rRESPA info]: [Mixing, shift, table, tail correction, restart, rRESPA info]:
Mixing is not relevant for this pair style, since as explained above, For atom type pairs I,J and I != J, the Z_i and Z_j coefficients
Z values are stored on a per-type basis, and both Zi and Zj are used can be mixed by taking Z_i and Z_j from the values specified for
explicitly in the ZBL formula. I == I and J == J cases. When used
with "hybrid/overlay"_pair_hybrid.html and pairs are assigned
to more than one sub-style, the mixing rule is not used and
each pair of types interacting with the ZBL sub-style
must be included in a pair_coeff command.
The "pair_modify"_pair_modify.html mix option has no effect on
the mixing behavior
The ZBL pair style does not support the "pair_modify"_pair_modify.html The ZBL pair style does not support the "pair_modify"_pair_modify.html
shift option, since the ZBL interaction is already smoothed to 0.0 at shift option, since the ZBL interaction is already smoothed to 0.0 at