ZiffRand

SimulationBuilder > Shared > RandNumGenerator?

Professor Robert Ziff's famed random number generator. If you don't want to have any correlations for very long times, this is just what the doctor ordered.

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Synopsis

This example shows an instance Ziff's random number generator being created in a Lennard-Jones simulation. It is used to randomize the particle velocities.

#include <glotzilla++.h>
class LennardJonesSimulationRandom : public MdSimulation
{
   public:
        LennardJonesSimulationRandom()
        {                                        
                IntializeParticles();
                SetInteraction(new LennardJones);
                SetForceRoutine(new BruteForce);
                SetBoundaryConditions(new PeriodicBoundary(10));
                SetIntegrationScheme(new VelocityVerletIntegrator);             
        }
        void IntializeParticles()
        {
                //get 216 x,y,z coordinates on a cubic lattice of density 0.85
                ipstream particle_pipe("randbox -n=216 -r=-4,4,-4,4,-4,4 -m=1.1 -i=1000000");
                ZiffRand *mRandomNumberGenerator = new ZiffRand();

                vec_t x;         
                //while we are getting x = {x,y,z} from pipe
                while(particle_pipe >> x)
                {
                        MdPointParticle *p = new MdPointParticle;                  
                        p -> SetPosition(x);
                        vec_t v = mRandomNumberGenerator -> ComputeRandomVecT(-sqrt(3.0), sqrt(3.0));
                        p -> SetVelocity(v);
                        AddParticle(p);
                }
                //close the pipe to mkcrystal
                particle_pipe.close();
        }
};

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References

Four-tap shift-registers sequence random number generators