97 lines
2.9 KiB
Plaintext
97 lines
2.9 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 spin command :h3
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min_style spin_oso_cg command :h3
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min_style spin_oso_lbfgs command :h3
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[Syntax:]
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min_style spin
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min_style spin_oso_cg
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min_style spin_oso_lbfgs :pre
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[Examples:]
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min_style spin_oso_lbfgs
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min_modify discrete_factor 10.0 line spin_none :pre
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[Description:]
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Apply a minimization algorithm to use when a "minimize"_minimize.html
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command is performed.
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Style {spin} defines a damped spin dynamics with an adaptive
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timestep, according to:
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:c,image(Eqs/min_spin_damping.jpg)
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with lambda a damping coefficient (similar to a Gilbert
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damping).
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Lambda can be defined by setting the {alpha_damp} keyword with the
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"min_modify"_min_modify.html command.
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The minimization procedure solves this equation using an
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adaptive timestep. The value of this timestep is defined
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by the largest precession frequency that has to be solved in the
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system:
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:c,image(Eqs/min_spin_timestep.jpg)
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with {|omega|_{max}} the norm of the largest precession frequency
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in the system (across all processes, and across all replicas if a
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spin/neb calculation is performed).
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Kappa defines a discretization factor {discrete_factor} for the
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definition of this timestep.
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{discrete_factor} can be defined with the "min_modify"_min_modify.html
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command.
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Style {spin_oso_cg} defines an orthogonal spin optimization
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(OSO) combined to a conjugate gradient (CG) algorithm.
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The "min_modify"_min_modify.html command can be used to
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couple the {spin_oso_cg} to a line search procedure, and to modify the
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discretization factor {discrete_factor}.
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Style {spin_oso_lbfgs} defines an orthogonal spin optimization
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(OSO) combined to a limited-memory Broyden-Fletcher-Goldfarb-Shanno
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(LBFGS) algorithm.
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By default, style {spin_oso_lbfgs} uses a line search procedure.
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The "min_modify"_min_modify.html command can be used to
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deactivate the line search procedure, and to modify the
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discretization factor {discrete_factor}.
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For more information about styles {spin_oso_cg} and {spin_oso_lbfgs},
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see their implementation reported in "(Ivanov)"_#Ivanov1.
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NOTE: All the {spin} styles replace the force tolerance by a torque
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tolerance. See "minimize"_minimize.html for more explanation.
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NOTE: The {spin_oso_cg} and {spin_oso_lbfgs} styles can be used
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for magnetic NEB calculations only if the line search procedure
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is deactivated. See "neb/spin"_neb_spin.html for more explanation.
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[Restrictions:]
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This minimization procedure is only applied to spin degrees of
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freedom for a frozen lattice configuration.
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[Related commands:]
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"min_style"_min_style.html, "minimize"_minimize.html,
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"min_modify"_min_modify.html
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[Default:]
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The option defaults are {alpha_damp} = 1.0 and {discrete_factor} =
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10.0.
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:line
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:link(Ivanov1)
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[(Ivanov)] Ivanov, Uzdin, Jonsson. arXiv preprint arXiv:1904.02669, (2019).
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