#include <modified_fire.h>

Inheritance diagram for pele::MODIFIED_FIRE:

Public Member Functions
	MODIFIED_FIRE (std::shared_ptr< pele::BasePotential > potential, pele::Array< double > &x0, double dtstart, double dtmax, double maxstep, size_t Nmin=5, double finc=1.1, double fdec=0.5, double fa=0.99, double astart=0.1, double tol=1e-4, bool stepback=true)
virtual	~MODIFIED_FIRE ()
void	one_iteration ()
void	initialize_func_gradient ()
void	set_func_gradient (double f, Array< double > grad)
void	reset (Array< double > &x0)

Detailed Description

An implementation of the *modified* FIRE optimization algorithm in c++.

The Fast Inertial Relaxation Engine is an optimization algorithm based on molecular dynamics with modifications to the velocity and adaptive time steps. The method is based on a blind skier searching for the bottom of a valley and is described and tested here:

Erik Bitzek, Pekka Koskinen, Franz Gaehler, Michael Moseler, and Peter Gumbsch. Phys. Rev. Lett. 97, 170201 (2006) http://link.aps.org/doi/10.1103/PhysRevLett.97.170201

This implementation of the algorithm differs significantly from the original algorithm in the order in which the steps are taken. Here we do the following:

-> initialise the velocities and gradients for some given coordinates -> set the velocity to the fire *inertial* velocity

Only then we use the MD integrator that here does things in this order:

-> compute the velocity difference and add it to the current velocity -> compute the new position given this velocity -> recompute gradient and energy

Once the integrator is done we continue following FIRE and compute

P = -g * f

here comes the other modification to the algorithm: if stepback is set to false then proceed just as the original FIRE algorithm prescribes, if stepback is set to true (default) then whenever P<=0 we undo the last step besides carrying out the operations defined by the original FIRE algorithm.

Definition at line 44 of file modified_fire.h.

Constructor & Destructor Documentation

pele::MODIFIED_FIRE::MODIFIED_FIRE	(	std::shared_ptr< pele::BasePotential >	potential,
		pele::Array< double > &	x0,
		double	dtstart,
		double	dtmax,
		double	maxstep,
		size_t	Nmin = `5`,
		double	finc = `1.1`,
		double	fdec = `0.5`,
		double	fa = `0.99`,
		double	astart = `0.1`,
		double	tol = `1e-4`,
		bool	stepback = `true`
	)

Constructor