org.opensourcephysics.sip.ch08.md
Class LJParticles

java.lang.Object
  org.opensourcephysics.sip.ch08.md.LJParticles

All Implemented Interfaces:

Drawable, ODE

public class LJParticles
extends java.lang.Object
implements Drawable, ODE

LJParticlesApp evolves a two-dimensional system of interacting particles via the Lennard-Jones potential using a Verlet ODESolver. getHeatCapacity method corrected based on bug report by Mike Cooke.

Field Summary

double[]	ax
double[]	ay
double	dt
java.lang.String	initialConfiguration
double	initialKineticEnergy
double	Lx
double	Ly
int	N
int	nx
int	ny
double	radius
double	rho
double[]	state
int	steps
double	t
double	totalKineticEnergyAccumulator
double	totalKineticEnergySquaredAccumulator
double	totalPotentialEnergyAccumulator
double	virialAccumulator

Constructor Summary

LJParticles()

Method Summary

void	computeAcceleration()
void	draw(DrawingPanel panel, java.awt.Graphics g) Draws a representation of an object in a drawing panel.
double	getHeatCapacity() Gets the heat capacity.
double	getMeanEnergy()
double	getMeanPressure()
double	getMeanTemperature()
void	getRate(double[] state, double[] rate) Gets the rate of change using the argument's state variables.
double[]	getState() Gets the state variables.
void	initialize()
void	resetAverages()
void	setRandomPositions()
void	setRectangularLattice()
void	setTriangularLattice()
void	setVelocities()
void	step(HistogramFrame xVelocityHistogram)

Methods inherited from class java.lang.Object

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

Field Detail

state

public double[] state

ax

public double[] ax

ay

public double[] ay

N

public int N

nx

public int nx

ny

public int ny

Lx

public double Lx

Ly

public double Ly

rho

public double rho

initialKineticEnergy

public double initialKineticEnergy

steps

public int steps

dt

public double dt

t

public double t

totalPotentialEnergyAccumulator

public double totalPotentialEnergyAccumulator

totalKineticEnergyAccumulator

public double totalKineticEnergyAccumulator

totalKineticEnergySquaredAccumulator

public double totalKineticEnergySquaredAccumulator

virialAccumulator

public double virialAccumulator

initialConfiguration

public java.lang.String initialConfiguration

radius

public double radius

Constructor Detail

LJParticles

public LJParticles()

Method Detail

initialize

public void initialize()

setRandomPositions

public void setRandomPositions()

setRectangularLattice

public void setRectangularLattice()

setTriangularLattice

public void setTriangularLattice()

setVelocities

public void setVelocities()

getMeanTemperature

public double getMeanTemperature()

getMeanEnergy

public double getMeanEnergy()

getMeanPressure

public double getMeanPressure()

getHeatCapacity

public double getHeatCapacity()

Gets the heat capacity. Errata: On page 276 in Eq. 8.11, after the equal sign, the first appearance of N should be 1/N and in Eq. 8.12 after the minus sign 1/N should be N. We thank Mike Cooke for pointing out this error.

Returns:

double

resetAverages

public void resetAverages()

computeAcceleration

public void computeAcceleration()

getRate

public void getRate(double[] state,
                    double[] rate)

Description copied from interface: ODE

Gets the rate of change using the argument's state variables. This method may be invoked many times with different intermediate states as an ODESolver is carrying out the solution.

Specified by:

getRate in interface ODE

Parameters:

state - the state array

rate - the rate array

getState

public double[] getState()

Description copied from interface: ODE

Gets the state variables. The getState method is invoked by an ODESolver to obtain the initial state of the system. The ODE solver advances the solution and then copies new values into the state array at the end of the solution step.

Specified by:

getState in interface ODE

Returns:

state the state

step

public void step(HistogramFrame xVelocityHistogram)

draw

public void draw(DrawingPanel panel,
                 java.awt.Graphics g)

Description copied from interface: Drawable

Draws a representation of an object in a drawing panel.

Specified by:

draw in interface Drawable