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3.13. Minimization styles

Classes that perform energy minimization derived from the Min class. New styles can be created to add new minimization algorithms to LAMMPS.

src/min_cg.cpp is an example of conjugate gradient minimization.

Here is a brief description of methods you define in your new derived class. See src/min.h for details.

Required	“pure” methods that must be overridden
setup_style	initialize minimizer-specific data structures
reset_vectors	connect internal xvec/fvec pointers to atom coordinates
iterate	perform the minimization iterations; returns stop-code

Optional	methods that have a default or base-class implementation
init	initialize the minimization before a run
setup	called before minimization starts
setup_minimal	minimal setup variant used for restarts
init_style	check style-specific conditions at init time
run	called by LAMMPS to drive the full minimization
force_clear	clear forces; override for GPU/Kokkos variants
energy_force	evaluate energy and forces; override for Kokkos
fnorm_sqr	return the squared force norm; override for spin styles
fnorm_inf	return the inf-norm of forces; override for spin styles
fnorm_max	return the max force norm; override for spin styles
modify_param	handle arguments from the min_modify command
memory_usage	tally of memory usage

The iterate() method must return one of the following integer stop-condition codes defined as an enum in src/min.h: MAXITER, MAXEVAL, ETOL, FTOL, DOWNHILL, ZEROALPHA, ZEROFORCE, ZEROQUAD, TRSMALL, INTERROR, TIMEOUT, or MAXVDOTF.

The line-search style used by the minimizer is controlled by the linestyle member, which takes values from the enum { BACKTRACK, QUADRATIC, FORCEZERO, SPIN_CUBIC, SPIN_NONE }.