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<li class="toctree-l2"><a class="reference internal" href="angle_amoeba.html">angle_style amoeba command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_charmm.html">angle_style charmm command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_class2.html">angle_style class2 command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_class2.html#angle-style-class2-p6-command">angle_style class2/p6 command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine.html">angle_style cosine command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_buck6d.html">angle_style cosine/buck6d command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_delta.html">angle_style cosine/delta command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_periodic.html">angle_style cosine/periodic command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_shift.html">angle_style cosine/shift command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_shift_exp.html">angle_style cosine/shift/exp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_squared.html">angle_style cosine/squared command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cosine_squared_restricted.html">angle_style cosine/squared/restricted command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_cross.html">angle_style cross command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_dipole.html">angle_style dipole command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_fourier.html">angle_style fourier command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_fourier_simple.html">angle_style fourier/simple command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_gaussian.html">angle_style gaussian command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_harmonic.html">angle_style harmonic command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_hybrid.html">angle_style hybrid command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_lepton.html">angle_style lepton command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_mesocnt.html">angle_style mesocnt command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_mm3.html">angle_style mm3 command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_none.html">angle_style none command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_quartic.html">angle_style quartic command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="angle_spica.html">angle_style spica command</a></li>
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<li class="toctree-l2 current"><a class="current reference internal" href="#">angle_style table command</a><ul>
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<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#examples">Examples</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#description">Description</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#restart-fix-modify-output-run-start-stop-minimize-info">Restart, fix_modify, output, run start/stop, minimize info</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#restrictions">Restrictions</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#related-commands">Related commands</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#default">Default</a></li>
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</ul>
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<li class="toctree-l2"><a class="reference internal" href="angle_zero.html">angle_style zero command</a></li>
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</ul>
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<li class="toctree-l1"><a class="reference internal" href="dihedrals.html">Dihedral Styles</a></li>
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<li class="toctree-l1"><a class="reference internal" href="impropers.html">Improper Styles</a></li>
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<li class="toctree-l1"><a class="reference internal" href="dumps.html">Dump Styles</a></li>
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<li class="toctree-l1"><a class="reference internal" href="fix_modify_atc_commands.html">fix_modify AtC commands</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Bibliography.html">Bibliography</a></li>
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<li class="breadcrumb-item active">angle_style table command</li>
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<p><span class="math notranslate nohighlight">\(\renewcommand{\AA}{\text{Å}}\)</span></p>
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<section id="angle-style-table-command">
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<span id="index-1"></span><span id="index-0"></span><h1>angle_style table command<a class="headerlink" href="#angle-style-table-command" title="Link to this heading"></a></h1>
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<p>Accelerator Variants: <em>table/omp</em></p>
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<section id="syntax">
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<h2>Syntax<a class="headerlink" href="#syntax" title="Link to this heading"></a></h2>
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<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">angle_style</span><span class="w"> </span><span class="n">table</span><span class="w"> </span><span class="n">style</span><span class="w"> </span><span class="n">N</span>
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</pre></div>
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</div>
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<ul class="simple">
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<li><p>style = <em>linear</em> or <em>spline</em> = method of interpolation</p></li>
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<li><p>N = use N values in table</p></li>
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</ul>
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</section>
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<section id="examples">
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<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading"></a></h2>
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<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">angle_style</span><span class="w"> </span><span class="n">table</span><span class="w"> </span><span class="n">linear</span><span class="w"> </span><span class="m">1000</span>
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<span class="k">angle_coeff</span><span class="w"> </span><span class="m">3</span><span class="w"> </span><span class="n">file.table</span><span class="w"> </span><span class="n">ENTRY1</span>
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</pre></div>
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</div>
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</section>
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<section id="description">
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<h2>Description<a class="headerlink" href="#description" title="Link to this heading"></a></h2>
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<p>Style <em>table</em> creates interpolation tables of length <em>N</em> from angle
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potential and derivative values listed in a file(s) as a function of
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angle The files are read by the <a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a>
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command.</p>
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<p>The interpolation tables are created by fitting cubic splines to the
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file values and interpolating energy and derivative values at each of
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<em>N</em> angles. During a simulation, these tables are used to interpolate
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energy and force values on individual atoms as needed. The
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interpolation is done in one of 2 styles: <em>linear</em> or <em>spline</em>.</p>
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<p>For the <em>linear</em> style, the angle is used to find 2 surrounding table
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values from which an energy or its derivative is computed by linear
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interpolation.</p>
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<p>For the <em>spline</em> style, a cubic spline coefficients are computed and
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stored at each of the <em>N</em> values in the table. The angle is used to
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find the appropriate set of coefficients which are used to evaluate a
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cubic polynomial which computes the energy or derivative.</p>
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<p>The following coefficients must be defined for each angle type via the
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<a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a> command as in the example above.</p>
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<ul class="simple">
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<li><p>filename</p></li>
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<li><p>keyword</p></li>
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</ul>
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<p>The filename specifies a file containing tabulated energy and
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derivative values. The keyword specifies a section of the file. The
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format of this file is described below.</p>
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<hr class="docutils" />
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<p>Suitable tables for use with this angle style can be created by LAMMPS
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itself from existing angle styles using the <a class="reference internal" href="angle_write.html"><span class="doc">angle_write</span></a> command. This can be useful to have a template file for
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testing the angle style settings and to build a compatible custom file.
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Another option to generate tables is the Python code in the
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<code class="docutils literal notranslate"><span class="pre">tools/tabulate</span></code> folder of the LAMMPS source code distribution.</p>
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<p>The format of a tabulated file is as follows (without the
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parenthesized comments):</p>
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<div class="highlight-none notranslate"><div class="highlight"><pre><span></span># Angle potential for harmonic (one or more comment or blank lines)
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HAM (keyword is the first text on line)
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N 181 FP 0 0 EQ 90.0 (N, FP, EQ parameters)
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(blank line)
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1 0.0 200.5 2.5 (index, angle, energy, derivative)
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2 1.0 198.0 2.5
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...
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181 180.0 0.0 0.0
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</pre></div>
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</div>
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<p>A section begins with a non-blank line whose first character is not a
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“#”; blank lines or lines starting with “#” can be used as comments
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between sections. The first line begins with a keyword which
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identifies the section. The line can contain additional text, but the
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initial text must match the argument specified in the
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<a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a> command. The next line lists (in any
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order) one or more parameters for the table. Each parameter is a
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keyword followed by one or more numeric values.</p>
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<p>The parameter “N” is required and its value is the number of table
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entries that follow. Note that this may be different than the <em>N</em>
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specified in the <a class="reference internal" href="angle_style.html"><span class="doc">angle_style table</span></a> command. Let
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Ntable = <em>N</em> in the angle_style command, and Nfile = “N” in the
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tabulated file. What LAMMPS does is a preliminary interpolation by
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creating splines using the Nfile tabulated values as nodal points. It
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uses these to interpolate as needed to generate energy and derivative
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values at Ntable different points. The resulting tables of length
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Ntable are then used as described above, when computing energy and
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force for individual angles and their atoms. This means that if you
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want the interpolation tables of length Ntable to match exactly what
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is in the tabulated file (with effectively no preliminary
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interpolation), you should set Ntable = Nfile.</p>
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<p>The “FP” parameter is optional. If used, it is followed by two values
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fplo and fphi, which are the second derivatives at the innermost and
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outermost angle settings. These values are needed by the spline
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construction routines. If not specified by the “FP” parameter, they
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are estimated (less accurately) by the first two and last two
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derivative values in the table.</p>
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<p>The “EQ” parameter is also optional. If used, it is followed by a the
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equilibrium angle value, which is used, for example, by the <a class="reference internal" href="fix_shake.html"><span class="doc">fix shake</span></a> command. If not used, the equilibrium angle is
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set to 180.0.</p>
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<p>Following a blank line, the next N lines list the tabulated values.
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On each line, the first value is the index from 1 to N, the second value is
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the angle value (in degrees), the third value is the energy (in energy
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units), and the fourth is -dE/d(theta) (also in energy units). The third
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term is the energy of the 3-atom configuration for the specified
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angle. The last term is the derivative of the energy with respect to
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the angle (in degrees, not radians). Thus the units of the last term
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are still energy, not force. The angle values must increase from one
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line to the next. The angle values must also begin with 0.0 and end
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with 180.0, i.e. span the full range of possible angles.</p>
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<p>Note that one file can contain many sections, each with a tabulated
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potential. LAMMPS reads the file section by section until it finds
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one that matches the specified keyword.</p>
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<hr class="docutils" />
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<p>Styles with a <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed on the <a class="reference internal" href="Speed_packages.html"><span class="doc">Accelerator packages</span></a>
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page. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.</p>
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<p>These accelerated styles are part of the GPU, INTEL, KOKKOS,
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OPENMP, and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the <a class="reference internal" href="Build_package.html"><span class="doc">Build package</span></a> page for more info.</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 class="reference internal" href="Run_options.html"><span class="doc">-suffix command-line switch</span></a> when you invoke LAMMPS, or you can use the
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<a class="reference internal" href="suffix.html"><span class="doc">suffix</span></a> command in your input script.</p>
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<p>See the <a class="reference internal" href="Speed_packages.html"><span class="doc">Accelerator packages</span></a> page for more
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instructions on how to use the accelerated styles effectively.</p>
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</section>
|
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<hr class="docutils" />
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<section id="restart-fix-modify-output-run-start-stop-minimize-info">
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<h2>Restart, fix_modify, output, run start/stop, minimize info<a class="headerlink" href="#restart-fix-modify-output-run-start-stop-minimize-info" title="Link to this heading"></a></h2>
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<p>This angle style writes the settings for the “angle_style table”
|
|
command to <a class="reference internal" href="restart.html"><span class="doc">binary restart files</span></a>, so a angle_style
|
|
command does not need to specified in an input script that reads a
|
|
restart file. However, the coefficient information is not stored in
|
|
the restart file, since it is tabulated in the potential files. Thus,
|
|
angle_coeff commands do need to be specified in the restart input
|
|
script.</p>
|
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</section>
|
|
<section id="restrictions">
|
|
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Link to this heading"></a></h2>
|
|
<p>This angle style can only be used if LAMMPS was built with the
|
|
MOLECULE package. See the <a class="reference internal" href="Build_package.html"><span class="doc">Build package</span></a> doc page
|
|
for more info.</p>
|
|
</section>
|
|
<section id="related-commands">
|
|
<h2>Related commands<a class="headerlink" href="#related-commands" title="Link to this heading"></a></h2>
|
|
<p><a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a>, <a class="reference internal" href="angle_write.html"><span class="doc">angle_write</span></a></p>
|
|
</section>
|
|
<section id="default">
|
|
<h2>Default<a class="headerlink" href="#default" title="Link to this heading"></a></h2>
|
|
<p>none</p>
|
|
</section>
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<footer><div class="rst-footer-buttons" role="navigation" aria-label="Footer">
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<a href="angle_spica.html" class="btn btn-neutral float-left" title="angle_style spica command" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a>
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<a href="angle_zero.html" class="btn btn-neutral float-right" title="angle_style zero command" accesskey="n" rel="next">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
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