Gibbs Ensemble MCExamination of Java Code. Volume Exchange

private void trialVolume() {

double v1Old = firstPhase.volume();

double v2Old = secondPhase.volume();

double hOld = firstPhase.potentialEnergy.currentValue()  + secondPhase.potentialEnergy.currentValue();

double vStep = (2.*rand.nextDouble()-1.)*maxVStep; //uniform step in volume

double v1New = v1Old + vStep;

double v2New = v2Old - vStep;

double v1Scale = v1New/v1Old;

double v2Scale = v2New/v2Old;

double r1Scale = Math.pow(v1Scale,1.0/(double)Simulation.D);

double r2Scale = Math.pow(v2Scale,1.0/(double)Simulation.D);

firstPhase.inflate(r1Scale); //perturb volumes

secondPhase.inflate(r2Scale);

double hNew = firstPhase.potentialEnergy.currentValue() //acceptance probability + secondPhase.potentialEnergy.currentValue();

if(hNew >= Double.MAX_VALUE ||

Math.exp(-(hNew-hOld)/temperature

+ firstPhase.moleculeCount*Math.log(v1Scale)

+ secondPhase.moleculeCount*Math.log(v2Scale))

< rand.nextDouble())

{ //reject; restore volumes

firstPhase.inflate(1.0/r1Scale);

secondPhase.inflate(1.0/r2Scale);

}

//accept; nothing more to do

}

public class IntegratorGEMC extends Integrator

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