dihedral.hpp File Reference

Routines to calculate the dihedral energy or/and force for a particle quadruple. More...

#include "config/config.hpp"
#include <utils/Vector.hpp>
#include <utils/constants.hpp>
#include <boost/optional.hpp>
#include <cmath>
#include <tuple>

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Classes
struct	DihedralBond
	Parameters for four-body angular potential (dihedral-angle potentials). More...

Functions
bool	calc_dihedral_angle (Utils::Vector3d const &a, Utils::Vector3d const &b, Utils::Vector3d const &c, Utils::Vector3d &aXb, double &l_aXb, Utils::Vector3d &bXc, double &l_bXc, double &cosphi, double &phi)
	Calculates the dihedral angle between particle quadruple p1, p2, p3 and p4.

Detailed Description

Routines to calculate the dihedral energy or/and force for a particle quadruple.

Note that usage of dihedrals increases the interaction range of bonded interactions to 2 times the maximal bond length!

Definition in file dihedral.hpp.

Function Documentation

calc_dihedral_angle()

bool calc_dihedral_angle ( Utils::Vector3d const &  a, Utils::Vector3d const &  b, Utils::Vector3d const &  c, Utils::Vector3d &  aXb, double &  l_aXb, Utils::Vector3d &  bXc, double &  l_bXc, double &  cosphi, double &  phi  )

inline

Calculates the dihedral angle between particle quadruple p1, p2, p3 and p4.

The dihedral angle is the angle between the planes specified by the particle triples (p1,p2,p3) and (p2,p3,p4). Vectors a, b and c are the bond vectors between consecutive particles. If the a,b or b,c are parallel the dihedral angle is not defined in which case the function returns true. Calling functions should check for that.

Parameters

[in]	a	Vector from p1 to p2
[in]	b	Vector from p2 to p3
[in]	c	Vector from p3 to p4
[out]	aXb	Vector product of a and b
[out]	l_aXb	|aXB|
[out]	bXc	Vector product of b and c
[out]	l_bXc	|bXc|
[out]	cosphi	Cosine of the dihedral angle
[out]	phi	Dihedral angle in the range [0, pi]

Returns

Whether the angle is undefined.

Definition at line 97 of file dihedral.hpp.

References Utils::Vector< T, N >::norm(), Utils::pi(), TINY_LENGTH_VALUE, TINY_SIN_VALUE, and vector_product().

Referenced by TabulatedDihedralBond::energy(), DihedralBond::energy(), TabulatedDihedralBond::forces(), and DihedralBond::forces().