P2DiscreteFeynmanHibbs

java.lang.Object
- etomica.potential.P2DiscreteFeynmanHibbs

All Implemented Interfaces:

IPotential, IPotentialAtomic, Potential2Spherical
```
public class P2DiscreteFeynmanHibbs
extends java.lang.Object
implements Potential2Spherical
```
Effective 2 body potential approximating the quantum behavior of atomic interactions. This is based on the same idea as Feynman-Hibbs effective potential (approximating the distribution of atomic centers with a Gaussian), but uses a weighted average of the potential evaluated at discrete points, rather than a Taylor series expansion. As such, it is less accurate at high temperatures (where the series works well because the probability distribution is narrow) but can work better at low temperature (where the series fails because the distribution is very wide).

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class P2DiscreteFeynmanHibbs.P2HeEmpericalQuantum

Nested Classes
Modifier and Type	Class	Description
`static class`	`P2DiscreteFeynmanHibbs.P2HeEmpericalQuantum`

Field Summary

Fields
Modifier and Type	Field	Description
`protected Boundary`	`boundary`
`protected Vector`	`dr`
`protected double`	`fac`
`protected double`	`mass`
`protected int`	`nPoints`
`protected Potential2Spherical`	`p2Classy`
`protected double`	`stepFactor`
`protected double`	`temperature`

Constructor Summary

Constructors
Constructor Description

P2DiscreteFeynmanHibbs(Space space, Potential2Spherical p2Classical)

Constructors
Constructor	Description
`P2DiscreteFeynmanHibbs(Space space, Potential2Spherical p2Classical)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected void`	`calcFacs()`
`double`	`energy(IAtomList atoms)`	Energy of the pair as given by the u(double) method
`double`	`getRange()`	Returns the range over which the potential applies.
`static void`	`main(java.lang.String[] args)`
`int`	`nBody()`	The number of atoms on which the potential depends.
`void`	`setBox(Box box)`	Informs the potential of the box on which it acts so that it can properly consider the boundaries.
`void`	`setMass(double m)`	Sets the mass; we assume the reduced mass is m/2 (correct for particles with identical mass).
`void`	`setNPoints(int nPoints)`
`void`	`setStepFactor(double stepFactor)`
`void`	`setTemperature(double temperature)`
`double`	`u(double r2)`	The pair energy u(r^2) with no truncation applied.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - p2Classy
```
protected final Potential2Spherical p2Classy
```
  - dr
```
protected final Vector dr
```
  - boundary
```
protected Boundary boundary
```
  - temperature
```
protected double temperature
```
  - mass
```
protected double mass
```
  - fac
```
protected double fac
```
  - stepFactor
```
protected double stepFactor
```
  - nPoints
```
protected int nPoints
```
- Constructor Detail
  - P2DiscreteFeynmanHibbs
```
public P2DiscreteFeynmanHibbs(Space space,
                              Potential2Spherical p2Classical)
```
- Method Detail
  - nBody
```
public int nBody()
```
    Description copied from interface: IPotential
    
    The number of atoms on which the potential depends.
    
    Specified by:
    
    nBody in interface IPotential
  - setNPoints
```
public void setNPoints(int nPoints)
```
  - setStepFactor
```
public void setStepFactor(double stepFactor)
```
  - calcFacs
```
protected void calcFacs()
```
  - setTemperature
```
public void setTemperature(double temperature)
```
  - setMass
```
public void setMass(double m)
```
    Sets the mass; we assume the reduced mass is m/2 (correct for particles with identical mass).
  - energy
```
public double energy(IAtomList atoms)
```
    Energy of the pair as given by the u(double) method
    
    Specified by:
    
    energy in interface IPotentialAtomic
  - u
```
public double u(double r2)
```
    Description copied from interface: Potential2Spherical
    
    The pair energy u(r^2) with no truncation applied.
    
    Specified by:
    
    u in interface Potential2Spherical
    
    Parameters:
    
    r2 - the square of the distance between the particles.
  - setBox
```
public void setBox(Box box)
```
    Description copied from interface: IPotential
    
    Informs the potential of the box on which it acts so that it can properly consider the boundaries.
    
    Specified by:
    
    setBox in interface IPotential
  - 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
  - main
```
public static void main(java.lang.String[] args)
```

Class P2DiscreteFeynmanHibbs

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

p2Classy

dr

boundary

temperature

mass

fac

stepFactor

nPoints

Constructor Detail

P2DiscreteFeynmanHibbs

Method Detail

nBody

setNPoints

setStepFactor

calcFacs

setTemperature

setMass

energy

u

setBox

getRange

main