"LAMMPS WWW Page"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)
:line

min_style spin command :h3
min_style spin/cg command :h3
min_style spin/lbfgs command :h3

[Syntax:]

min_style spin 
min_style spin/cg 
min_style spin/lbfgs :pre

[Examples:]

min_style  spin/lbfgs
min_modify line spin_cubic discrete_factor 10.0 :pre

[Description:]

Apply a minimization algorithm to use when a "minimize"_minimize.html
command is performed.

Style {spin} defines a damped spin dynamics with an adaptive
timestep, according to:

:c,image(Eqs/min_spin_damping.jpg)

with lambda a damping coefficient (similar to a Gilbert
damping).
Lambda can be defined by setting the {alpha_damp} keyword with the
"min_modify"_min_modify.html command.

The minimization procedure solves this equation using an
adaptive timestep. The value of this timestep is defined
by the largest precession frequency that has to be solved in the
system:

:c,image(Eqs/min_spin_timestep.jpg)

with {|omega|_{max}} the norm of the largest precession frequency
in the system (across all processes, and across all replicas if a
spin/neb calculation is performed).

Kappa defines a discretization factor {discrete_factor} for the
definition of this timestep.
{discrete_factor} can be defined with the "min_modify"_min_modify.html
command.

Style {spin/cg} defines an orthogonal spin optimization
(OSO) combined to a conjugate gradient (CG) algorithm. 
The "min_modify"_min_modify.html command can be used to
couple the {spin/cg} to a line search procedure, and to modify the 
discretization factor {discrete_factor}.
By default, style {spin/cg} does not employ the line search procedure 
and uses the adaptive time-step technique in the same way as style {spin}.

Style {spin/lbfgs} defines an orthogonal spin optimization
(OSO) combined to a limited-memory Broyden-Fletcher-Goldfarb-Shanno 
(L-BFGS) algorithm.
By default, style {spin/lbfgs} does not employ line search procedure.
If the line search procedure is not used then the discrete factor defines
the maximum root mean squared rotation angle of spins by equation {pi/(5*Kappa)}.
The default value for Kappa is 10.
The {spin_cubic} line search can improve the convergence of the 
{spin/lbfgs} algorithm.

The "min_modify"_min_modify.html command can be used to
activate the line search procedure, and to modify the
discretization factor {discrete_factor}. 

For more information about styles {spin/cg} and {spin/lbfgs}, 
see their implementation reported in "(Ivanov)"_#Ivanov1.

NOTE: All the {spin} styles replace the force tolerance by a torque
tolerance. See "minimize"_minimize.html for more explanation. 

NOTE: The {spin/cg} and {spin/lbfgs} styles can be used
for magnetic NEB calculations only if the line search procedure
is deactivated. See "neb/spin"_neb_spin.html for more explanation. 

[Restrictions:] 

This minimization procedure is only applied to spin degrees of
freedom for a frozen lattice configuration.

[Related commands:]

"min_style"_min_style.html, "minimize"_minimize.html,
"min_modify"_min_modify.html

[Default:]

The option defaults are {alpha_damp} = 1.0, {discrete_factor} =
10.0, {line} = spin_none and {norm} = euclidean.

:line

:link(Ivanov1)
[(Ivanov)] Ivanov, Uzdin, Jonsson. arXiv preprint arXiv:1904.02669, (2019).
