CCSi, CCC), that specify parameters for all permutations of the two
elements interacting in three-body configurations. Thus for 3
elements, 27 entries would be required, etc.</p>
<p>Depending on the particular version of the Vashishta potential, the
values of these parameters may be keyed to the identities of zero,
one, two, or three elements. In order to make the input file format
unambiguous, general, and simple to code, LAMMPS uses a slightly
confusing method for specifying parameters. All parameters are
divided into two classes: two-body and three-body. Two-body and
three-body parameters are handled differently, as described below.
The two-body parameters are H, eta, lambda1, D, lambda4, W, rc, gamma,
and r0. They appear in the above formulae with two subscripts. The
parameters Zi and Zj are also classified as two-body parameters, even
though they only have 1 subscript. The three-body parameters are B,
C, costheta0. They appear in the above formulae with three
subscripts. Two-body and three-body parameters are handled
differently, as described below.</p>
<p>The first element in each entry is the center atom in a three-body
interaction, while the second and third elements are two neighbor
atoms. Three-body parameters for a central atom I and two neighbors J
and K are taken from the IJK entry. Note that even though three-body
parameters do not depend on the order of J and K, LAMMPS stores
three-body parameters for both IJK and IKJ. The user must ensure that
these values are equal. Two-body parameters for an atom I interacting
with atom J are taken from the IJJ entry, where the 2nd and 3rd
elements are the same. Thus the two-body parameters for Si interacting
with C come from the SiCC entry. Note that even though two-body
parameters (except possibly gamma and r0 in U3) do not depend on the
order of the two elements, LAMMPS will get the Si-C value from the
SiCC entry and the C-Si value from the CSiSi entry. The user must
ensure that these values are equal. Two-body parameters appearing in
entries where the 2nd and 3rd elements are different are stored but
never used. It is good practice to enter zero for these values. Note
that the three-body function U3 above contains the two-body parameters
gamma and r0. So U3 for a central C atom bonded to an Si atom and a
second C atom will take three-body parameters from the CSiC entry, but
two-body parameters from the CCC and CSiSi entries.</p>
<hr class="docutils" />
<p>Styles with a <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in <a class="reference internal" href="Section_accelerate.html"><span class="doc">Section 5</span></a>
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.</p>
<p>These accelerated styles are part of the GPU, USER-INTEL, 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 class="std std-ref">Making LAMMPS</span></a> section for more info.</p>
<p>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <a class="reference internal" href="Section_start.html#start-7"><span class="std std-ref">-suffix command-line switch</span></a> when you invoke LAMMPS, or you can
use the <a class="reference internal" href="suffix.html"><span class="doc">suffix</span></a> command in your input script.</p>
<p>See <a class="reference internal" href="Section_accelerate.html"><span class="doc">Section 5</span></a> of the manual for
more instructions on how to use the accelerated styles effectively.</p>
<p>For atom type pairs I,J and I != J, where types I and J correspond to
two different element types, mixing is performed by LAMMPS as
described above from values in the potential file.</p>
<p>This pair style does not support the <a class="reference internal" href="pair_modify.html"><span class="doc">pair_modify</span></a>
shift, table, and tail options.</p>
<p>This pair style does not write its information to <a class="reference internal" href="restart.html"><span class="doc">binary restart files</span></a>, since it is stored in potential files. Thus, you
need to re-specify the pair_style and pair_coeff commands in an input
script that reads a restart file.</p>
<p>This pair style can only be used via the <em>pair</em> keyword of the
<a class="reference internal" href="run_style.html"><span class="doc">run_style respa</span></a> command. It does not support the
Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>.