Package etomica.potential

Class P4TorsionDreiding

java.lang.Object

etomica.potential.Potential

etomica.potential.P4TorsionDreiding

All Implemented Interfaces:

IPotential, IPotentialAtomic, PotentialSoft

public class P4TorsionDreiding
extends Potential
implements PotentialSoft

Simple 4-body soft bond-angle for Dreiding potential U(phi) = (1/2) * Vjk * {1 - cos [njk (phi - phiEq)]} where Vjk is the rotation barrier (always +ve) [unit Kelvin] njk is the periodicity (an integer) phiEq is the equilibrium dihedral angle [unit radians]

Field Summary

Fields

Modifier and Type	Field	Description
protected double	beta
protected Boundary	boundary
protected Vector3D	dr12
protected Vector3D	dr23
protected Vector3D	dr34
protected Vector3D	dra
protected Vector3D	drb
protected Vector3D	drbxa
protected Vector[]	gradient
protected int	n
protected double	phiEq

Fields inherited from class etomica.potential.Potential

space

Constructor Summary

Constructors

Constructor	Description
P4TorsionDreiding(Space space, double phiEq, double beta, int n)

Method Summary

Modifier and Type	Method	Description
double	du(IAtomList atomSet)
static double	dudphi(int i, double cosp, double sinp)
double	energy(IAtomList atomSet)	Returns the interaction energy between the given atoms.
double	getBeta()
int	getN()
double	getPhi()
double	getRange()	Returns the range over which the potential applies.
Vector[]	gradient(IAtomList atoms)	Returns the gradient of the potential as it applies to each atom in the given AtomSet, indicating how the energy would change as the position of the first atom is varied.
Vector[]	gradient(IAtomList atomSet, Tensor pressureTensor)	Returns the same gradient as gradient(AtomSet) and also adds in the contribution of the AtomSet to the pressureTensor.
void	setBeta(double newBeta)
void	setBox(Box box)	Informs the potential of the box on which it acts.
void	setN(int newN)
void	setPhi(double newPhi)
double	virial(IAtomList atomSet)

Methods inherited from interface etomica.potential.IPotential

nBody

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from class etomica.potential.Potential

nBody

Field Detail

dr12

protected final Vector3D dr12

dr23

protected final Vector3D dr23

dr34

protected final Vector3D dr34

dra

protected final Vector3D dra

drb

protected final Vector3D drb

drbxa

protected final Vector3D drbxa

gradient

protected final Vector[] gradient

phiEq

protected double phiEq

beta

protected double beta

n

protected int n

boundary

protected Boundary boundary

Constructor Detail

P4TorsionDreiding

public P4TorsionDreiding(Space space,
                         double phiEq,
                         double beta,
                         int n)

Method Detail

virial

public double virial(IAtomList atomSet)

Specified by:

virial in interface PotentialSoft

gradient

public Vector[] gradient(IAtomList atomSet,
                         Tensor pressureTensor)

Description copied from interface: PotentialSoft

Returns the same gradient as gradient(AtomSet) and also adds in the contribution of the AtomSet to the pressureTensor. Their contribution is added to the given Tensor. This combined method exists for computational efficiency. Calculating the pressureTensor is generally trivial once the gradient is known but often requires intermediate information.

Specified by:

gradient in interface PotentialSoft

gradient

public Vector[] gradient(IAtomList atoms)

Description copied from interface: PotentialSoft

Returns the gradient of the potential as it applies to each atom in the given AtomSet, indicating how the energy would change as the position of the first atom is varied. The method is allowed to return an array of Vectors with fewer elements than the number of atoms in the AtomSet.

Specified by:

gradient in interface PotentialSoft

Returns:

setBox

public void setBox(Box box)

Description copied from class: Potential

Informs the potential of the box on which it acts. Typically this requires at least that it update the nearestImageTransformer of its coordinatePair (if it uses one), e.g.: cPair.setNearestImageTransformer(box.boundary());

Specified by:

setBox in interface IPotential

Specified by:

setBox in class Potential

energy

public double energy(IAtomList atomSet)

Description copied from class: Potential

Returns the interaction energy between the given atoms. There might be 0, 1, 2 or more atoms in the AtomSet.

Specified by:

energy in interface IPotentialAtomic

Specified by:

energy in class Potential

du

public double du(IAtomList atomSet)

setPhi

public void setPhi(double newPhi)

getPhi

public double getPhi()

setBeta

public void setBeta(double newBeta)

getBeta

public double getBeta()

setN

public void setN(int newN)

getN

public int getN()

dudphi

public static double dudphi(int i,
                            double cosp,
                            double sinp)

getRange

public double getRange()

Description copied from interface: IPotential

Returns the range over which the potential applies. IAtoms with a greater separation do not interact.

Specified by:

getRange in interface IPotential

Specified by:

getRange in class Potential