Esempio n. 1
0
		public override void CalculateForceField(ParticleEnsemble ensemble)
		{

			//variable declarations
			double posXi, posYi;
			double posXj, posYj;
			double LJxf,  LJyf;
			double ijSeparation = 0.0, LJforce = 0.0, PotentialEnergy = 0.0;
			int j, kk, ctr, dimensions = 2;
  
			//variable initializations

			int BoxHeight = ensemble.GetBoxHeight();
			int BoxWidth = ensemble.GetBoxWidth();
			double MaxForce = ensemble.GetMaxForceThreshold();
			double MinForce = -1.0 * (ensemble.GetMaxForceThreshold());
  
			// initialize vectors holding forces
			for (int i = 0; i < ensemble.GetNumberOfParticles(); ++i)
			{
				LJxforces[i]=0.0;
				LJyforces[i]=0.0;
			}

			for (int i = 0; i < ensemble.GetNumberOfParticles(); ++i)
			{

				for (j = (i + 1); j < ensemble.GetNumberOfParticles(); ++j)
				{
      
					//    get the interparticle separation distances
					ijSeparation = ensemble.GetInterParticleSeparation(i, j);
						
					//		update the radial distribution function
			  //			pParticleSet->UpdateRadialDistributionFunction((int)(ijSeparation));
			
					double cutoffDistance = MinimumDistance[i, j];
			
					if (ijSeparation < cutoffDistance) {
	
						// for each particle, change the appropriate element of the setWithinRangeOfAnotherParticle vector to true

						posXi = ensemble.GetXParticlePosition(i);
						posYi = ensemble.GetYParticlePosition(i);

						posXj = ensemble.GetXParticlePosition(j);
						posYj = ensemble.GetYParticlePosition(j);
												
						//        PotentialEnergy += LJenergyTermA[i][j]/(pow(ijSeparation,12.0))+LJenergyTermB[i][j]/pow(ijSeparation,6.0)+epsilon;
						LJforce = (posXj - posXi) * (LJgradientTermA[i, j] / Math.Pow(ijSeparation, 13.0) + LJgradientTermB[i, j] / Math.Pow(ijSeparation, 7.0)) / ijSeparation;
						if (Math.Abs(LJforce) > MaxForce || Math.Abs(LJforce) < MinForce) { LJforce = 0.0; }    // error check for real-time stability...
						else if(double.IsNaN(LJforce) || double.IsInfinity(LJforce)){LJforce = 0.0;} // error check for real-time stability...
				
						LJxforces[i] += LJforce;
						LJxforces[j] += -1.0*LJforce;
						//        cout << "x "<< i << " " << j << " " << LJforce << endl; 
				//				cout << "i " << i << " LJxforces[i] " << LJxforces[i] << " j " << j <<  " LJxforces[j] " << LJxforces[j] << endl;
						//        cout << "xi:=" << posXi << ";" << "xj:=" << posXj << ";" << "yi:=" << posYi << ";" << "yj:=" << posYj << ";" << LJxforces[i] << endl;
						LJforce = (posYj - posYi) * (LJgradientTermA[i, j] / Math.Pow(ijSeparation, 13.0) + LJgradientTermB[i, j] / Math.Pow(ijSeparation, 7.0)) / ijSeparation;

						if (Math.Abs(LJforce) > MaxForce || Math.Abs(LJforce) < MinForce) { LJforce = 0.0; }    // error check for real-time stability...
						else if (double.IsNaN(LJforce) || double.IsInfinity(LJforce)) { LJforce = 0.0; } // error check for real-time stability...
				
						LJyforces[i] += LJforce;
						LJyforces[j] += -1.0*LJforce;

						ensemble.SetParticlesWithinRange(i, j);
						ensemble.SetParticlesWithinRange(j, i);
				
						//        cout << i << " " << j << endl; 
					}
					else{
						ensemble.SetParticlesNotWithinRange(i, j);
						ensemble.SetParticlesNotWithinRange(j, i);			
					}
				}        
			}
	
			// set the forces in the Particle Ensemble Object
			ensemble.AddXForces(LJxforces);
			ensemble.AddYForces(LJyforces);
			// set the potential energy
			ensemble.AddPotentialEnergy(PotentialEnergy);
		}