git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14970 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp
2016-05-09 20:20:41 +00:00
parent 04177fcd07
commit 7baaf2dfe2
31 changed files with 47 additions and 43 deletions

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@ -240,11 +240,11 @@ particles will match the target values specified by Tstart/Tstop and
Pstart/Pstop.</p>
<p>The equations of motion used are those of Shinoda et al in
<a class="reference internal" href="pair_sdk.html#shinoda"><span class="std std-ref">(Shinoda)</span></a>, which combine the hydrostatic equations of
Martyna, Tobias and Klein in <a class="reference internal" href="fix_rigid.html#martyna"><span class="std std-ref">(Martyna)</span></a> with the strain
Martyna, Tobias and Klein in <a class="reference internal" href="#martyna"><span class="std std-ref">(Martyna)</span></a> with the strain
energy proposed by Parrinello and Rahman in
<a class="reference internal" href="fix_nh_eff.html#parrinello"><span class="std std-ref">(Parrinello)</span></a>. The time integration schemes closely
<a class="reference internal" href="#parrinello"><span class="std std-ref">(Parrinello)</span></a>. The time integration schemes closely
follow the time-reversible measure-preserving Verlet and rRESPA
integrators derived by Tuckerman et al in <a class="reference internal" href="run_style.html#tuckerman"><span class="std std-ref">(Tuckerman)</span></a>.</p>
integrators derived by Tuckerman et al in <a class="reference internal" href="fix_pimd.html#tuckerman"><span class="std std-ref">(Tuckerman)</span></a>.</p>
<hr class="docutils" />
<p>The thermostat parameters for fix styles <em>nvt</em> and <em>npt</em> is specified
using the <em>temp</em> keyword. Other thermostat-related keywords are
@ -257,7 +257,7 @@ ramped value during the run from <em>Tstart</em> to <em>Tstop</em>. The <em>Tda
parameter is specified in time units and determines how rapidly the
temperature is relaxed. For example, a value of 10.0 means to relax
the temperature in a timespan of (roughly) 10 time units (e.g. tau or
fmsec or psec - see the <span class="xref doc">units</span> command). The atoms in the
fmsec or psec - see the <a class="reference internal" href="units.html"><span class="doc">units</span></a> command). The atoms in the
fix group are the only ones whose velocities and positions are updated
by the velocity/position update portion of the integration.</p>
<div class="admonition note">
@ -267,7 +267,7 @@ of <em>Tdamp</em>. If <em>Tdamp</em> is too small, the temperature can fluctuat
wildly; if it is too large, the temperature will take a very long time
to equilibrate. A good choice for many models is a <em>Tdamp</em> of around
100 timesteps. Note that this is NOT the same as 100 time units for
most <span class="xref doc">units</span> settings.</p>
most <a class="reference internal" href="units.html"><span class="doc">units</span></a> settings.</p>
</div>
<hr class="docutils" />
<p>The barostat parameters for fix styles <em>npt</em> and <em>nph</em> is specified
@ -302,7 +302,7 @@ simulation box must be triclinic, even if its initial tilt factors are
<em>Tdamp</em> parameter, determining the time scale on which pressure is
relaxed. For example, a value of 10.0 means to relax the pressure in
a timespan of (roughly) 10 time units (e.g. tau or fmsec or psec - see
the <span class="xref doc">units</span> command).</p>
the <a class="reference internal" href="units.html"><span class="doc">units</span></a> command).</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">A Nose-Hoover barostat will not work well for arbitrary values
@ -311,7 +311,7 @@ fluctuate wildly; if it is too large, the pressure will take a very
long time to equilibrate. A good choice for many models is a <em>Pdamp</em>
of around 1000 timesteps. However, note that <em>Pdamp</em> is specified in
time units, and that timesteps are NOT the same as time units for most
<span class="xref doc">units</span> settings.</p>
<a class="reference internal" href="units.html"><span class="doc">units</span></a> settings.</p>
</div>
<p>Regardless of what atoms are in the fix group (the only atoms which
are time integrated), a global pressure or stress tensor is computed
@ -402,7 +402,7 @@ freedom. A value of 0 corresponds to no thermostatting of the
barostat variables.</p>
<p>The <em>mtk</em> keyword controls whether or not the correction terms due to
Martyna, Tuckerman, and Klein are included in the equations of motion
<a class="reference internal" href="fix_rigid.html#martyna"><span class="std std-ref">(Martyna)</span></a>. Specifying <em>no</em> reproduces the original
<a class="reference internal" href="#martyna"><span class="std std-ref">(Martyna)</span></a>. Specifying <em>no</em> reproduces the original
Hoover barostat, whose volume probability distribution function
differs from the true NPT and NPH ensembles by a factor of 1/V. Hence
using <em>yes</em> is more correct, but in many cases the difference is
@ -411,7 +411,7 @@ negligible.</p>
scheme at little extra cost. The initial and final updates of the
thermostat variables are broken up into <em>tloop</em> substeps, each of
length <em>dt</em>/<em>tloop</em>. This corresponds to using a first-order
Suzuki-Yoshida scheme <a class="reference internal" href="run_style.html#tuckerman"><span class="std std-ref">(Tuckerman)</span></a>. The keyword <em>ploop</em>
Suzuki-Yoshida scheme <a class="reference internal" href="fix_pimd.html#tuckerman"><span class="std std-ref">(Tuckerman)</span></a>. The keyword <em>ploop</em>
does the same thing for the barostat thermostat.</p>
<p>The keyword <em>nreset</em> controls how often the reference dimensions used
to define the strain energy are reset. If this keyword is not used,