Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F108391223
min_modify.html
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Wed, Apr 16, 11:38
Size
2 KB
Mime Type
text/html
Expires
Fri, Apr 18, 11:38 (2 d)
Engine
blob
Format
Raw Data
Handle
25539601
Attached To
rLAMMPS lammps
min_modify.html
View Options
<HTML>
<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>
</CENTER>
<HR>
<H3>min_modify command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>min_modify keyword values ...
</PRE>
<UL><LI>one or more keyword/value pairs may be listed
<PRE>keyword = <I>linestyle</I> or <I>dmin</I> or <I>dmax</I> or <I>lineiter</I>
<I>linestyle</I> value = <I>secant</I> or <I>scan</I>
<I>dmin</I> value = min
min = minimum distance for line search to move (distance units)
<I>dmax</I> value = max
max = maximum distance for line search to move (distance units)
<I>lineiter</I> value = N
N = max number of iterations in a line search
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>min_modify linestyle scan dmin 0.001 dmax 0.2
min_modify lineiter 5
</PRE>
<P><B>Description:</B>
</P>
<P>This command sets parameters that affect the minimization algorithms.
The various settings may effect the convergence rate and overall
number of force evaulations required by a minimization, so users can
experiment with these parameters to tune their minimizations.
</P>
<P>The <I>linestyle</I> sets the algorithm used for 1d line searches at each
outer iteration of the minimizer. The <I>secant</I> style uses two
successive force/energy evaluations to create a parabola and pick its
minimum as an estimate of the next iteration's 1d minimum. The <I>scan</I>
style starts its 1d search at <I>dmin</I> and doubles the distance along
the line at which the energy is computed until the minimum is passed.
It continues only as far as <I>dmax</I>. Normally, the <I>secant</I> method
should find more accurate 1d minimums in less iterations, but the
<I>scan</I> method can be more robust.
</P>
<P>The <I>dmin</I> and <I>dmax</I> settings are both used by the <I>scan</I> line search
as described above. For the <I>secant</I> line search, only the <I>dmin</I>
value is used to pick an initial point to begin the secant
approximation.
</P>
<P>The <I>lineiter</I> setting is used by the <I>secant</I> algorithm to limit its
iterations. The smaller the setting, the more inaccurate the line
search becomes. Nonlinear conjugate gradient is not thought to
require high-accuracy line searches in order to converge efficiently.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "min_style.html">min_style</A>, <A HREF = "minimize.html">minimize</A>
</P>
<P><B>Default:</B>
</P>
<P>The option defaults are linestyle = secant, dmin = 1.0e-5, dmax = 0.1,
and lineiter = 10.
</P>
</HTML>
Event Timeline
Log In to Comment