forked from lijiext/lammps
141 lines
5.2 KiB
Plaintext
141 lines
5.2 KiB
Plaintext
"LAMMPS WWW Page"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Commands_all.html)
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:line
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min_style command :h3
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[Syntax:]
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min_style style :pre
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style = {cg} or {hftn} or {sd} or {quickmin} or {fire} or {spin} or {spin/cg} or {spin/lbfgs} :ul
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[Examples:]
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min_style cg
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min_style spin
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min_style fire :pre
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[Description:]
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Choose a minimization algorithm to use when a "minimize"_minimize.html
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command is performed.
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Style {cg} is the Polak-Ribiere version of the conjugate gradient (CG)
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algorithm. At each iteration the force gradient is combined with the
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previous iteration information to compute a new search direction
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perpendicular (conjugate) to the previous search direction. The PR
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variant affects how the direction is chosen and how the CG method is
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restarted when it ceases to make progress. The PR variant is thought
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to be the most effective CG choice for most problems.
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Style {hftn} is a Hessian-free truncated Newton algorithm. At each
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iteration a quadratic model of the energy potential is solved by a
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conjugate gradient inner iteration. The Hessian (second derivatives)
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of the energy is not formed directly, but approximated in each
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conjugate search direction by a finite difference directional
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derivative. When close to an energy minimum, the algorithm behaves
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like a Newton method and exhibits a quadratic convergence rate to high
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accuracy. In most cases the behavior of {hftn} is similar to {cg},
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but it offers an alternative if {cg} seems to perform poorly. This
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style is not affected by the "min_modify"_min_modify.html command.
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Style {sd} is a steepest descent algorithm. At each iteration, the
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search direction is set to the downhill direction corresponding to the
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force vector (negative gradient of energy). Typically, steepest
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descent will not converge as quickly as CG, but may be more robust in
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some situations.
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Style {quickmin} is a damped dynamics method described in
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"(Sheppard)"_#Sheppard, where the damping parameter is related to the
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projection of the velocity vector along the current force vector for
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each atom. The velocity of each atom is initialized to 0.0 by this
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style, at the beginning of a minimization.
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Style {fire} is a damped dynamics method described in
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"(Bitzek)"_#Bitzek, which is similar to {quickmin} but adds a variable
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timestep and alters the projection operation to maintain components of
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the velocity non-parallel to the current force vector. The velocity
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of each atom is initialized to 0.0 by this style, at the beginning of
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a minimization.
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Style {spin} is a damped spin dynamics with an adaptive
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timestep.
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Style {spin/cg} uses an orthogonal spin optimization (OSO)
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combined to a conjugate gradient (CG) approach to minimize spin
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configurations.
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Style {spin/lbfgs} uses an orthogonal spin optimization (OSO)
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combined to a limited-memory Broyden-Fletcher-Goldfarb-Shanno
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(LBFGS) approach to minimize spin configurations.
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See the "min/spin"_min_spin.html doc page for more information
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about the {spin}, {spin/cg} and {spin/lbfgs} styles.
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Either the {quickmin} and {fire} styles are useful in the context of
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nudged elastic band (NEB) calculations via the "neb"_neb.html command.
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Either the {spin}, {spin/cg} and {spin/lbfgs} styles are useful
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in the context of magnetic geodesic nudged elastic band (GNEB) calculations
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via the "neb/spin"_neb_spin.html command.
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NOTE: The damped dynamic minimizers use whatever timestep you have
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defined via the "timestep"_timestep.html command. Often they will
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converge more quickly if you use a timestep about 10x larger than you
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would normally use for dynamics simulations.
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NOTE: The {quickmin}, {fire}, {hftn}, and {cg/kk} styles do not yet
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support the use of the "fix box/relax"_fix_box_relax.html command or
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minimizations involving the electron radius in "eFF"_pair_eff.html
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models.
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:line
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Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} 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 "Speed packages"_Speed_packages.html doc
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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.
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These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
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USER-OMP and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the "Build
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package"_Build_package.html doc page for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the "-suffix command-line
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switch"_Run_options.html when you invoke LAMMPS, or you can use the
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"suffix"_suffix.html command in your input script.
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See the "Speed packages"_Speed_packages.html doc page for more
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instructions on how to use the accelerated styles effectively.
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:line
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[Restrictions:] none
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[Related commands:]
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"min_modify"_min_modify.html, "minimize"_minimize.html, "neb"_neb.html
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[Default:]
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min_style cg :pre
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:line
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:link(Sheppard)
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[(Sheppard)] Sheppard, Terrell, Henkelman, J Chem Phys, 128, 134106
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(2008). See ref 1 in this paper for original reference to Qmin in
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Jonsson, Mills, Jacobsen.
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:link(Bitzek)
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[(Bitzek)] Bitzek, Koskinen, Gahler, Moseler, Gumbsch, Phys Rev Lett,
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97, 170201 (2006).
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