colvarmodule::atom_group::group_force_object Class Reference

A helper class for applying forces on an atom group in a way that is aware of the fitting group. NOTE: you are encouraged to use get_group_force_object() to get an instance of group_force_object instead of constructing directly. More...

#include <colvaratoms.h>

Collaboration diagram for colvarmodule::atom_group::group_force_object:

Public Member Functions
	group_force_object (cvm::atom_group *ag)
	Constructor of group_force_object. More...
	~group_force_object ()
	Destructor of group_force_object.
void	add_atom_force (size_t i, const cvm::rvector &force)
	Apply force to atom i. More...

Private Member Functions
void	apply_force_with_fitting_group ()

Private Attributes
cvm::atom_group *	m_ag
cvm::atom_group *	m_group_for_fit
bool	m_has_fitting_force

Detailed Description

A helper class for applying forces on an atom group in a way that is aware of the fitting group. NOTE: you are encouraged to use get_group_force_object() to get an instance of group_force_object instead of constructing directly.

Constructor & Destructor Documentation

group_force_object()

cvm::atom_group::group_force_object::group_force_object

(

cvm::atom_group *

ag

)

Constructor of group_force_object.

Parameters

ag	The pointer to the atom group that forces will be applied on.

Member Function Documentation

add_atom_force()

void cvm::atom_group::group_force_object::add_atom_force	(	size_t	i,
		const cvm::rvector &	force
	)

Apply force to atom i.

Parameters

i	The i-th of atom in the atom group.
force	The force being added to atom i.

The function can be used as follows,

// In your colvar::cvc::apply_force() loop of a component:
auto ag_force = atoms->get_group_force_object();
for (ia = 0; ia < atoms->size(); ia++) {
  const cvm::rvector f = compute_force_on_atom_ia();
  ag_force.add_atom_force(ia, f);
}

There are actually two scenarios under the hood: (i) If the atom group does not have a fitting group, then the force is added to atom i directly; (ii) If the atom group has a fitting group, the force on atom i will just be temporary stashed into ag->group_forces. At the end of the loop of apply_force(), the destructor ~group_force_object() will be called, which then call apply_force_with_fitting_group(). The forces on the main group will be rotated back by multiplying ag->group_forces with the inverse rotation. The forces on the fitting group (if enableFitGradients is on) will be calculated by calling calc_fit_forces.

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The documentation for this class was generated from the following files:

• colvaratoms.h
• colvaratoms.cpp