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lammps/doc/min_style.txt
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"LAMMPS WWW Page"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
min_style command :h3
[Syntax:]
min_style style :pre
style = {cg} or {hftn} or {sd} :ul
[Examples:]
min_style cg
min_style hftn :pre
[Description:]
Choose a minimization algorithm to use when a "minimize"_minimize.html
command is performed.
Style {cg} is the Polak-Ribiere version of the conjugate gradient (CG)
algorithm. At each iteration the force gradient is combined with the
previous iteration information to compute a new search direction
perpendicular (conjugate) to the previous search direction. The PR
variant affects how the direction is chosen and how the CG method is
restarted when it ceases to make progress. The PR variant is thought
to be the most effective CG choice.
Style {hftn} is a Hessian-free truncated Newton algorithm. At each
iteration a quadratic model of the energy potential is solved by a
conjugate gradient inner iteration. The Hessian (second derivatives)
of the energy is not formed directly, but approximated in each
conjugate search direction by a finite difference directional
derivative. When close to an energy minimum, the algorithm behaves
like a Newton method and exhibits a quadratic convergence rate to high
accuracy. In most cases the behavior of {hftn} is similar to {cg},
but it offers another minimizer alternative if {cg} seems to perform
poorly. This style is not affected by the
"min_modify"_min_modify.html command.
Style {sd} is a steepest descent algorithm. At each iteration, the
search direction is set to the downhill direction corresponding to the
force vector (negative gradient of energy). Typically, steepest
descent will not converge as quickly as CG, but may be more robust in
some situations.
[Restrictions:] none
[Related commands:]
"min_modify"_min_modify.html, "minimize"_minimize.html
[Default:]
min_style cg :pre
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