/* fcc crystal - periodic Rafii-Tarar and Sutton potential */
/* coded by Ikeuchi Mitsuru      */
/* ver 0.0.1   2003.10.19        */
/* ver 0.0.2   2003.10.20 bug fixed */
/* ver 0.0.3   2004.02.18  improved pannel layout */

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class fccCrystalPRTS extends Applet
  implements MouseListener, MouseMotionListener,
    ItemListener, AdjustmentListener, Runnable {

/*-------------------------------------- define gloval -----*/

  Choice cm1,ctc,cvw;
  Scrollbar scr,scp;
  Thread th = null;

  Dimension dim;
  Image imgOff;
  Graphics gOff;

  int sleepTime = 50;
  double sgm = 3.4e-10;       /* L-J sigma for Ar (m)   */
  double dispScale = 30.0/sgm;

  double xMax0 = 6.0*sgm;     /* x-Box size in (m)      */
  double yMax0 = 6.0*sgm;     /* y-Box size in (m)      */
  double zMax0 = 6.0*sgm;     /* z-Box size in (m)      */
  double xMax = xMax0;
  double yMax = yMax0;
  double zMax = zMax0;


  int Nmt = 8*8*8/2;         /* number of molecules    */
  int NN = Nmt + 1;
  double t = 0.0;              /* time (s)               */
  double dt = 0.5*1.0e-15;     /* time division (s)      */

  double volRatio = 1.0;
  int tempMode = 1;
  double contTemp = 100.0;
  double contPress = 1.0*1.0e5;
  double scale = 1.0;
  int dispMode = 0;


  int dgX, dgY, dgXb, dgYb;
  double cx = 0.5*xMax;
  double cy = 0.5*yMax;
  double cz = 0.5*zMax;
  double theta = -20.0*3.14/180.0;
  double fai = 10.0*3.14/180.0;
  double dtheta = 0.0*3.14/180.0;
  double pai = 3.1415926536;

  double AA = 1.0e-10;
  double AU = 1.661e-27;
  double SuttonChen[][] = {
  /*  atom    0 mass     1 m   2 n    3 eps      4 c     5 a  */
  /* 0 Ni */ {  58.71*AU, 6.0,  9.0, 1.5713e-2,  39.755, 3.52 },
  /* 1 Cu */ {  63.54*AU, 6.0,  9.0, 1.2386e-2,  39.755, 3.61 },
  /* 2 Rh */ { 102.91*AU, 6.0, 12.0, 4.9371e-3, 145.658, 3.80 },
  /* 3 Pd */ { 106.40*AU, 7.0, 12.0, 4.1790e-3, 108.526, 3.89 },
  /* 4 Ag */ { 107.87*AU, 6.0, 12.0, 2.5415e-3, 145.658, 4.09 },
  /* 5 Ir */ { 192.20*AU, 6.0, 14.0, 2.4489e-3, 337.831, 3.84 },
  /* 6 Pt */ { 195.09*AU, 8.0, 10.0, 1.9835e-2,  34.428, 3.92 },
  /* 7 Au */ { 196.97*AU, 8.0, 10.0, 1.2794e-2,  34.428, 4.08 },
  /* 8 Pb */ { 207.19*AU, 7.0, 10.0, 5.5772e-3,  45.882, 4.95 },
  /* 9 Al */ {  26.98*AU, 6.0,  7.0, 3.3307e-2,  16.460, 4.05 }
  };
  int MAT1 = 0; /* Ni */
  int MAT2 = 9; /* Al */
  int kindMax = 10;

  double RTSm[][] = new double[kindMax][kindMax];
  double RTSn[][] = new double[kindMax][kindMax];
  double RTSa[][] = new double[kindMax][kindMax];
  double RTSeps[][] = new double[kindMax][kindMax];

  double rcutoff = 2.0*3.52e-10;


  int kind[] = new int[NN];       /* i-th molec kind */
  double xx[] = new double[NN];   /* i-th x-position */
  double yy[] = new double[NN];   /* i-th y-position */
  double zz[] = new double[NN];   /* i-th z-position */
  double vx[] = new double[NN];   /* i-th x-velocity */
  double vy[] = new double[NN];   /* i-th y-velocity */
  double vz[] = new double[NN];   /* i-th z-velocity */
  double ffx[] = new double[NN];  /* i-th x-force    */
  double ffy[] = new double[NN];  /* i-th y-force    */
  double ffz[] = new double[NN];  /* i-th z-force    */
  double fbx[] = new double[NN];  /* i-th x-force before dt */
  double fby[] = new double[NN];  /* i-th y-force before dt */
  double fbz[] = new double[NN];  /* i-th z-force before dt */


  int reg[][] = new int[NN][680];   /* registration */
  double rijReg[][] = new double[NN][680];   /* registration */

  int regNr[][] = new int[NN][680];   /* registration */

  int srtz[][] = new int[2][NN];   /* z-sort work space */

  int rdf[][] = new int[4][120];

  double virial[][] = new double[3][256];
  double memTemp[] = new double[256];
  int virialp = 0;

  double px[] = new double[NN]; 
  double py[] = new double[NN]; 
  double pz[] = new double[NN]; 

  double wkx[] = new double[8]; 
  double wky[] = new double[8]; 
  double wkz[] = new double[8]; 

  double pwkx[] = new double[8]; 
  double pwky[] = new double[8]; 
  double pwkz[] = new double[8]; 

  int boxp[][] = {
   {0,1},{0,2},{0,4},{1,3},{1,5},{2,3},{2,6},{4,5},{4,6},{3,7},{5,7},{6,7}
  };

/*----------------------------- applet control functions -----*/

  public void init() {
    resize(630,300);
    setBackground(Color.white);

    dim = getSize();
    imgOff = createImage(dim.width,dim.height);
    gOff = imgOff.getGraphics();

    cm1 = new Choice();
    cm1.addItem("Ni");  cm1.addItem("Cu"); cm1.addItem("Rh"); cm1.addItem("Pd");
    cm1.addItem("Ag"); cm1.addItem("Ir"); cm1.addItem("Pt"); cm1.addItem("Au");
    cm1.addItem("Pb"); cm1.addItem("Al");
    cm1.addItemListener(this); 

    ctc = new Choice();
    ctc.addItem("adiabatic"); ctc.addItem("T scaling");
    ctc.addItemListener(this); 
    ctc.select("T scaling");

    cvw = new Choice();
    cvw.addItem("ball"); cvw.addItem("line"); cvw.addItem("both");
    cvw.addItem("temp"); cvw.addItem("real");
    cvw.addItemListener(this); 

    scr= new Scrollbar(Scrollbar.HORIZONTAL,10,10,1,210);
    scr.addAdjustmentListener(this);

    scp= new Scrollbar(Scrollbar.HORIZONTAL,30,10,1,210);
    scp.addAdjustmentListener(this);

    addMouseListener(this);  
    addMouseMotionListener(this);

    setLayout(new BorderLayout());
    Panel pnl = new Panel();
    pnl.setLayout(new GridLayout(1,6,5,0));
    pnl.add(cm1);
    pnl.add(ctc);
    pnl.add(cvw);
    pnl.add(new Label("  "));
    pnl.add(scr);
    pnl.add(scp);
    add(pnl,"North");

    setRTS();
    setInitialPosition();
  }

  public void start() {
    if (th == null) {
      th = new Thread(this);
      th.start();
    }
  }

  public void stop() {
    if (th != null) {
      th.stop();
      th = null;
    }
  }


  public void itemStateChanged(ItemEvent ev){
    if (ev.getSource() == ctc){
      tempMode = ctc.getSelectedIndex();
    } else if (ev.getSource() == cm1){
      MAT1 = cm1.getSelectedIndex();
      t = 0.0;
      setInitialPosition();
      setWaku();
    } else if (ev.getSource() == cvw){
      dispMode = cvw.getSelectedIndex();
    }
  }

  public void adjustmentValueChanged(AdjustmentEvent ev){
    if (ev.getSource() == scr) { 
      contTemp = 10.0*(double)(scr.getValue());
      vAjustment();
    } else if (ev.getSource() == scp) { 
      contPress = 1.0e5*(double)(scp.getValue());
    }
  }

  public void mousePressed(MouseEvent ev){ }
  public void mouseReleased(MouseEvent ev){
    dgXb = 0; dgYb = 0;
    dgX = 0; dgY = 0;
  }
  public void mouseClicked(MouseEvent ev){ }
  public void mouseEntered(MouseEvent ev){ } 
  public void mouseExited (MouseEvent ev){ }

  public void mouseMoved  (MouseEvent ev){ }

  public void mouseDragged(MouseEvent ev){
    dgXb = dgX; dgYb = dgY;
    dgX=ev.getX();
    dgY=ev.getY();
    if (dgXb==0 && dgYb==0) {
      dgXb = dgX; dgYb = dgY;
    }
    theta += 0.5*3.14/180.0*(dgX-dgXb);
    fai += 0.5*3.14/180.0*(dgY-dgYb);
  }

  public void run() {
    while (th != null) {
      try {
        calcposition();
        offPaint();
        repaint();
        Thread.sleep(sleepTime);
      } catch (InterruptedException e) { }
    }
  }

  public void update(Graphics g) {
    paint(g);
  }

  public void paint(Graphics g) {
    g.drawImage(imgOff,0,0,this);
  }

/* ----------------------------- offPaint -------------------- */

  void offPaint() {
    int i,j,k,jj,farPoint,im,ip;
    int gx,gy,gz,g2x,g2y,gbx,gby, gb;
    double sc,sa,sb,tmp,tm,bl,clr,mtm;

    gOff.setColor(Color.white);
    gOff.fillRect(0,0,dim.width,dim.height);

    setWaku();
    setRadialDistribution();
    rotate(theta,fai);
    zSort();
    tmp = temperature();

    gbx = 60;
    gby = 80;
    sc = dispScale*scale;
    sa = 0.5*sc*0.707*SuttonChen[MAT1][5]*1.0e-10;
    sb = 0.5*sc*0.707*SuttonChen[MAT2][5]*1.0e-10;

    farPoint = findMin();
    for (i=0; i<12; i++) {
      gx = (int)(sc*pwkx[boxp[i][0]])+gbx;
      gy = (int)(sc*pwky[boxp[i][0]])+gby;
      g2x = (int)(sc*pwkx[boxp[i][1]])+gbx;
      g2y = (int)(sc*pwky[boxp[i][1]])+gby;
      if (boxp[i][0]==farPoint || boxp[i][1]==farPoint) { 
        gOff.setColor(Color.lightGray);
        gOff.drawLine(gx,gy, g2x, g2y);
      } 
    }

    if (dispMode==0) {

      for (i=0; i<Nmt; i++) {
        j = srtz[0][i];
        gx = (int)(sc*px[j])+gbx;
        gy = (int)(sc*py[j])+gby;
        gz = (int)(sa*(0.4*pz[j]/zMax+0.6));
        gOff.setColor(Color.getHSBColor(0.33f,0.95f,(float)(0.4*pz[j]/zMax+0.4)));
        gOff.fillOval(gx-gz/2,gy-gz/2, gz, gz);
      }

    } else if (dispMode==1) {

      for (i=0; i<Nmt; i++) {
        j = srtz[0][i];
        gx = (int)(sc*px[j])+gbx;
        gy = (int)(sc*py[j])+gby;
        gz = (int)(sa*(0.4*pz[j]/zMax+0.6));

        for(k=1;k<reg[i][0];k++) {
          jj = reg[j][k];
          if (jj>j) {
            if (distance(j,jj)<1.15*0.707*0.5*(SuttonChen[kind[j]][5]+SuttonChen[kind[jj]][5])*1.0e-10) {
              g2x = (int)(sc*px[jj])+gbx;
              g2y = (int)(sc*py[jj])+gby;
              gOff.setColor(Color.gray);
              gOff.drawLine(gx,gy, g2x, g2y);
            }
          }
        }

      }

    } else if (dispMode==2) {

      bl = 0.90*sa*1.0e-10;
      for (i=0; i<Nmt; i++) {
        j = srtz[0][i];
        gx = (int)(sc*px[j])+gbx;
        gy = (int)(sc*py[j])+gby;

        for(k=1;k<reg[i][0];k++) {
          jj = reg[j][k];
          if (jj>j) {
            if (distance(j,jj)<1.15*0.707*0.5*(SuttonChen[kind[j]][5]+SuttonChen[kind[jj]][5])*1.0e-10) {
              g2x = (int)(sc*px[jj])+gbx;
              g2y = (int)(sc*py[jj])+gby;
              gOff.setColor(Color.gray);
              gOff.drawLine(gx,gy, g2x, g2y);
            }
          }
        }
        gz = (int)(sa*(0.4*pz[j]/zMax+0.6));
        gOff.setColor(Color.getHSBColor(0.33f,0.95f,(float)(0.4*pz[j]/zMax+0.4)));
        gOff.fillOval(gx-gz/2,gy-gz/2, gz, gz);
      }

    } else if (dispMode==3) {

      for (i=0; i<Nmt; i++) {
        j = srtz[0][i];
        gx = (int)(sc*px[j])+gbx;
        gy = (int)(sc*py[j])+gby;
        gz = (int)(sa*(0.4*pz[j]/zMax+0.6));
        clr = 0.33;
        tm = temp(j)/1000.0 + 0.3;
        if(tm>0.99) {
          tm = 0.99;
        }
        gOff.setColor(Color.getHSBColor((float)clr,0.9f,(float)tm));
        gOff.fillOval(gx-gz/2,gy-gz/2, gz, gz);
      }

    }else if (dispMode==4) {

      for (i=0; i<Nmt; i++) {
        j = srtz[0][i];
        gx = (int)(sc*px[j])+gbx;
        gy = (int)(sc*py[j])+gby;
        gz = (int)(2.0*sa*(0.4*pz[j]/zMax+0.6));
        gOff.setColor(Color.getHSBColor(0.33f,0.95f,(float)(0.4*pz[j]/zMax+0.4)));
        gOff.fillOval(gx-gz/2,gy-gz/2, gz, gz);
      }

    }


    for (i=0; i<12; i++) {
      gx = (int)(sc*pwkx[boxp[i][0]])+gbx;
      gy = (int)(sc*pwky[boxp[i][0]])+gby;
      g2x = (int)(sc*pwkx[boxp[i][1]])+gbx;
      g2y = (int)(sc*pwky[boxp[i][1]])+gby;
      if (boxp[i][0]!=farPoint && boxp[i][1]!=farPoint) { 
        gOff.setColor(Color.gray);
        if (tempMode==2) {
          if (tmp>contTemp) {
            gOff.setColor(Color.black); 
          } else {
            gOff.setColor(Color.red);
          }
        }
        gOff.drawLine(gx,gy, g2x, g2y);
      }
    }

    gbx = 400;
    gby = 60;
    gOff.setColor(Color.gray);
    for (i=0; i<100; i+=20) {
      gOff.drawLine(gbx+i,gby, gbx+i, gby+200);
    }
    gOff.drawLine(gbx,gby+100, gbx+100, gby+100);
    gOff.setColor(Color.black);
    gOff.drawRect(gbx,gby,100,200);
    gOff.drawString("0",gbx-5,gby+215);
    gOff.drawString("5 A",gbx+90,gby+215);
    gOff.setColor(Color.cyan);
    for (i=0; i<100; i++) {
      if (rdf[0][i]>0) {
        gOff.setColor(Color.getHSBColor(0.33f,0.95f,0.95f));
        gOff.drawLine(gbx+i,gby+200-rdf[1][i]/2, gbx+i, gby+200);
        gOff.setColor(Color.getHSBColor(0.66f,0.95f,0.95f));
        gOff.drawLine(gbx+i,gby+200-rdf[2][i]/2, gbx+i, gby+200);
        gOff.setColor(Color.getHSBColor(0.12f,0.95f,0.95f));
        gOff.drawLine(gbx+i,gby+200-rdf[3][i]/2, gbx+i, gby+200);
      }
    }

    gOff.setColor(Color.black);
    gOff.drawString("atom",630/6*0+10,40);
    gOff.drawString("temp control",630/6*1+10,40);
    gOff.drawString("view",630/6*2+10,40);
    gOff.drawString("cont T="+contTemp+"K",630/6*4+10,40);
    gOff.drawString("cont P="+(int)(contPress/1.0e3+0.5)+"kPa",630/6*5+10,40);
    gb = 520;
    mtm = meanTemp();
    gOff.setColor(Color.black);
    gOff.drawString("a="+SuttonChen[MAT1][5]+"A",gb,80);
    gOff.setColor(Color.blue);
    gOff.drawString("t="+Math.floor(t*1.0e15+0.5)+"(fs)",gb,100);
    gOff.drawString("L="+(int)(xMax*1.0e13+0.5)/10.0+" pm",gb,120);
    gOff.drawString("V="+(int)(xMax*yMax*zMax*1.0e29+0.5)/100.0+" nm3",gb,140);
    gOff.drawString("T="+tmp+" K",gb,160);
    gOff.drawString("P="+(int)(pressure1()/1.0e6+0.5)+"MPa",gb,180);
    gOff.drawString("<T>="+(int)(mtm*10+0.5)/10.0+" K",gb,200);
    gOff.drawString("<P>="+(int)(pressure()/1.0e6+0.5)+"MPa",gb,220);
    gOff.drawString("nk<T>="+(int)(Nmt*1.38e-23*mtm/(xMax*yMax*zMax)/1.0e6+0.5)+"MPa",gb,240);

  }


  double distance(int i,int j) {
    double x,y,z;

    x = xx[i]-xx[j];
    y = yy[i]-yy[j];
    z = zz[i]-zz[j];

    return(Math.sqrt(x*x+y*y+z*z));
  }



/*----------------------------------  findMin()  ----------*/

  int findMin() {
    int i,im;
    double m;

    im = 0; m = pwkz[im];
    for (i=0; i<8; i++) {
      if (pwkz[i]<m) {
        m = pwkz[i];
        im = i;
      }
    }
    return(im);
  }

/*-------------------------------------  sort z  ----------*/

  void zSort() {
    int i,j,w;

    for (i=0; i<Nmt; i++) {
      j = srtz[0][i];
      srtz[1][i] = (int)(32767.0*pz[j]/zMax);
    } 
    for (i=0; i<Nmt; i++) {
      for (j=0; j<Nmt-1; j++) {
        if (srtz[1][j]>srtz[1][j+1]) {
          w = srtz[0][j]; srtz[0][j]=srtz[0][j+1]; srtz[0][j+1]=w;
          w = srtz[1][j]; srtz[1][j]=srtz[1][j+1]; srtz[1][j+1]=w;
        }
      }
    }    
  }

  void zSortInit() {
    int i,j,w;

    for (i=0; i<Nmt; i++) {
      srtz[0][i] = i;
      srtz[1][i] = (int)(32767.0*pz[i]/zMax);
    } 
    for (i=0; i<Nmt; i++) {
      for (j=0; j<Nmt-1; j++) {
        if (srtz[1][j]>srtz[1][j+1]) {
          w = srtz[0][j]; srtz[0][j]=srtz[0][j+1]; srtz[0][j+1]=w;
          w = srtz[1][j]; srtz[1][j]=srtz[1][j+1]; srtz[1][j+1]=w;
        }
      }
    }    
  }

/*-------------------------------------  rotate  ----------*/

  void rotate(double th,double fi) {
    int i;
    double cosTh,sinTh,cosFi,sinFi;

    cosTh = Math.cos(th); sinTh = Math.sin(th);
    cosFi = Math.cos(fi); sinFi = Math.sin(fi);
    for (i=0; i<Nmt; i++) {
      py[i] = cosFi*(yy[i]-cy)+sinFi*(zz[i]-cz) + cy; 
      pz[i] = -sinFi*(yy[i]-cy)+cosFi*(zz[i]-cz) + cz;
    } 
    for (i=0; i<Nmt; i++) {
      px[i] = cosTh*(xx[i]-cx)+sinTh*(pz[i]-cz) + cx; 
      pz[i] = -sinTh*(xx[i]-cx)+cosTh*(pz[i]-cz) + cz;
    } 

    for (i=0; i<8; i++) {
      pwky[i] = cosFi*(wky[i]-cy)+sinFi*(wkz[i]-cz) + cy; 
      pwkz[i] = -sinFi*(wky[i]-cy)+cosFi*(wkz[i]-cz) + cz;
    } 
    for (i=0; i<8; i++) {
      pwkx[i] = cosTh*(wkx[i]-cx)+sinTh*(pwkz[i]-cz) + cx; 
      pwkz[i] = -sinTh*(wkx[i]-cx)+cosTh*(pwkz[i]-cz) + cz;
    }  
  }

/*-------------------------------------  setWaku  ---------*/

  void setWaku() {
    int i,ix,iy,iz;

    i=0;

    for (ix=0; ix<2; ix++) {
      for (iy=0; iy<2; iy++) {
        for (iz=0; iz<2; iz++) {
          wkx[i] = -0.5*sgm+(xMax+sgm)*(double)(ix);
          wky[i] = -0.5*sgm+(yMax+sgm)*(double)(iy);
          wkz[i] = -0.5*sgm+(zMax+sgm)*(double)(iz);
          i += 1;
        }
      }
    }
  }

/*-------------------------------------  statictics  ----------*/

  double temperature() {
    int i;
    double s;

    s = 0.0; 
    for (i=0; i<Nmt; i++) {
      s += 0.5*SuttonChen[kind[i]][0]*(vx[i]*vx[i] + vy[i]*vy[i] + vz[i]*vz[i]);
    }
    return ((double)Math.floor(s/((double)Nmt*1.5*1.38e-23)*10.0)/10.0 );
  }

  double temp(int ii) {
    double s;

    s = 0.5*SuttonChen[kind[ii]][0]*(vx[ii]*vx[ii] + vy[ii]*vy[ii] + vz[ii]*vz[ii]);
    return (s/(1.5*1.38e-23));
  }

/*-------------------------------------  v ajustment  ---------*/

  void vAjustment() {
    int i;
    double tmp, r;

    tmp = temperature();
    r = Math.sqrt(contTemp/tmp);
    for (i=0; i<Nmt; i++) {
      vx[i] = r*vx[i];
      vy[i] = r*vy[i];
      vz[i] = r*vz[i];
    }
  }


/*-------------------- radial distribution function  ----------*/

  void setRadialDistribution() {
    int i,j,k,ir;
    double xi,xj,yi,yj,zi,zj;
    double r2,rij;

    for (i=0; i<120; i++) {
      rdf[0][i]=0;
      rdf[1][i]=0;
      rdf[2][i]=0;
      rdf[3][i]=0;
    }

    for (i=0; i<Nmt; i++) {
      for(k=1;k<reg[i][0];k++) {
        j = reg[i][k];
        xi = xx[i]; xj = xx[j]; yi = yy[i]; yj = yy[j]; zi = zz[i]; zj = zz[j];
        if (xi-xj>0.5*xMax) { xj += xMax; };
        if (xi-xj<-0.5*xMax) { xj -= xMax; };
        if (yi-yj>0.5*yMax) { yj += yMax; };
        if (yi-yj<-0.5*yMax) { yj -= yMax; };
        if (zi-zj>0.5*zMax) { zj += zMax; };
        if (zi-zj<-0.5*zMax) { zj -= zMax; }; 
        r2=(xi-xj)*(xi-xj)+(yi-yj)*(yi-yj)+(zi-zj)*(zi-zj);
        rij = Math.sqrt(r2);
        if (rij<5.0e-10) {
          ir = (int)(Math.floor(rij*2.0e11+0.49999));
          rdf[0][ir] +=1;
          if (kind[i]==MAT1 && kind[j]==MAT1) {
            rdf[1][ir] +=1;
          } else if (kind[i]==MAT2 && kind[j]==MAT2) {
            rdf[2][ir] +=1;
          } else {
            rdf[3][ir] +=1;
          }
        }
      }
    }

  }

/*-------------------- pressure  ----------*/

  void initVirial() {
    int i;

    for (i=0; i<256; i++) {
      virial[0][i] = 0.0;
      virial[1][i] = 0.0;
      virial[2][i] = 0.0;
      memTemp[i] = 0.0;
    }
    virialp = 0;
  }

  void setVirial() {
    int i;
    double xVir,yVir,zVir;

    xVir = 0.0; yVir = 0.0; zVir = 0.0;
    for (i=0; i<Nmt; i++) {
      xVir += ffx[i]*xx[i];
      yVir += ffy[i]*yy[i];
      zVir += ffz[i]*zz[i];
    }

    virial[0][virialp] = xVir;
    virial[1][virialp] = yVir;
    virial[2][virialp] = zVir;
    memTemp[virialp] = temperature();
    virialp = (virialp+1)%256;
  }


  double meanTemp() {
    int i;
    double st,tm;

    st = 0;
    for (i=0; i<256; i++) {
      st += memTemp[i];
    }
    tm = st/256.0;
    return( tm );
  }

  double pressure() {
    int i;
    double s,vir,tm,vol,p;

    s = 0.0;
    for (i=0; i<256; i++) {
      s += virial[0][i]+virial[1][i]+virial[2][i];
    }
    vir = s/256.0;
    tm = meanTemp();
    vol = xMax*yMax*zMax;
    p = (Nmt*1.38e-23*tm+vir/3.0)/vol;
    return( p );
  }

  double pressure10() {
    int i,ip;
    double s,vir,tm,vol,p;

    s = 0.0;
    for (i=0; i<10; i++) {
      ip = (virialp+256-10+i)%256;
      s += virial[0][ip]+virial[1][ip]+virial[2][ip];
    }
    vir = s/10.0;
    tm = meanTemp();
    vol = xMax*yMax*zMax;
    p = (Nmt*1.38e-23*tm+vir/3.0)/vol;
    return( p );
  }

  double pressure1() {
    int ip;
    double s,vir,tm,vol,p;

    ip = (virialp-1+256)%256;
    s = virial[0][ip]+virial[1][ip]+virial[2][ip];

    vir = s/10.0;
    tm = meanTemp();
    vol = xMax*yMax*zMax;
    p = (Nmt*1.38e-23*tm+vir/3.0)/vol;
    return( p );
  }

/*-------------------------------  vol control   -------------*/

  void volControl() {
    double d,pr,r,x,y,z;

    d = dt*1.0;
    pr = pressure1();
    if (pr<0.0) {
      pr = 0.0;
    }
    r = Math.pow(pr/contPress,0.3333);
    if (r<0.5) {
      r=0.5;
    }
    x = r*xMax;
    y = r*yMax;
    z = r*zMax;

    if (x>xMax+d) {
      x = xMax + d;
    } else if (x<xMax-d) {
      x = xMax - d;
    }
    xMax = x;

    if (y>yMax+d) {
      y = yMax + d;
    } else if (y<yMax-d) {
      y = yMax - d;
    }
    yMax = y;

    if (z>zMax+d) {
      z = zMax + d;
    } else if (z<zMax-d) {
      z = zMax - d;
    }
    zMax = z;

    cx = 0.5*xMax;
    cy = 0.5*yMax;
    cz = 0.5*zMax;

  }



/*-------------------------  set RTS   ---------*/

  void setRTS() {
    int i,j;

    for (i=0; i<kindMax; i++) {
      for (j=0; j<kindMax; j++) {
        RTSm[i][j]=0.5*(SuttonChen[i][1]+SuttonChen[j][1]);
        RTSn[i][j]=0.5*(SuttonChen[i][2]+SuttonChen[j][2]);
        RTSa[i][j]=Math.sqrt(SuttonChen[i][5]*SuttonChen[j][5]);
        RTSeps[i][j]=Math.sqrt(SuttonChen[i][3]*SuttonChen[j][3]);
      }
    }

  }

/*-------------------------  set initial condition   ---------*/

  void setInitialPosition(){
    int i,ix,iy,iz; 
    double a,b;

    rcutoff = 2.0*SuttonChen[MAT1][5]*1.0e-10;
    if (rcutoff < 2.0*SuttonChen[MAT2][5]*1.0e-10) {
      rcutoff = 2.0*SuttonChen[MAT2][5]*1.0e-10;
    }

    a = 0.5*SuttonChen[MAT1][5]*1.0e-10;

    xMax = 8.0*a;
    yMax = 8.0*a;
    zMax = 8.0*a;

    i = 0;
    for (ix=0; ix<8; ix++) {
      for (iy=0; iy<8; iy++) {
        for (iz=0; iz<8; iz++) {
          if ((ix+iy+iz)%2==0) {
            kind[i] = MAT1;
            xx[i] = a*(double)(ix)+0.5*a;
            yy[i] = a*(double)(iy)+0.5*a;
            zz[i] = a*(double)(iz)+0.5*a;
            vx[i] = 100.0*Math.random()-50.0;
            vy[i] = 100.0*Math.random()-50.0;
            vz[i] = 100.0*Math.random()-50.0;
            ffx[i] = 0.0;
            ffy[i] = 0.0;
            ffz[i] = 0.0;
            fbx[i] = 0.0;
            fby[i] = 0.0;
            fbz[i] = 0.0;
            i += 1;
          }
        }
      }
    }

    initVirial();
    zSortInit();
  }

/*-------------------------------  molecules motion   ---------*/

  void calcposition(){
    int i;

    if (tempMode==1) {
      vAjustment();
    }

    regNear();
    for (i=0; i<10; i++) {
      timeEvolution();
      volControl();
    }
    setVirial();
  }

  void timeEvolution(){
    int i; 
    double rr,tmp;

    t = t + dt;

    rr = 1.0;
    if (tempMode==2) {
      tmp = temperature();
      rr = Math.sqrt(contTemp/tmp);
      if (rr<0.5) { rr = 0.5; } else if (rr>1.2){ rr=1.2; };
    }

    for (i=0; i<Nmt; i++) {
      xx[i] += vx[i]*dt+0.5*dt*dt*ffx[i]/SuttonChen[kind[i]][0];
      yy[i] += vy[i]*dt+0.5*dt*dt*ffy[i]/SuttonChen[kind[i]][0];
      zz[i] += vz[i]*dt+0.5*dt*dt*ffz[i]/SuttonChen[kind[i]][0];
      fbx[i] = ffx[i];
      fby[i] = ffy[i];
      fbz[i] = ffz[i];
    }

    forceCalc();

    for (i=0; i<Nmt; i++) {
      vx[i] += 0.5*dt*(ffx[i]+fbx[i])/SuttonChen[kind[i]][0];
      vy[i] += 0.5*dt*(ffy[i]+fby[i])/SuttonChen[kind[i]][0];
      vz[i] += 0.5*dt*(ffz[i]+fbz[i])/SuttonChen[kind[i]][0];
    }

    for (i=0; i<Nmt; i++) {

      if (xx[i] < 0.0) { 
        xx[i] += xMax; 
      }
      if (xx[i] > xMax) {
        xx[i] -= xMax; 
      }
      if (yy[i] < 0.0) { 
        yy[i] += yMax; 
      }
      if (yy[i] > yMax) {
        yy[i] -= yMax; 
      }
      if (zz[i] < 0.0) { 
        zz[i] += zMax; 
      }
      if (zz[i] > zMax) {
        zz[i] -= zMax; 
      }

    }
  }

  void forceCalc() {
    int i,j,k;
    double xi,xj,yi,yj,zi,zj;
    double fpi,rij,f,fxij,fyij,fzij;

    for(i=0;i<Nmt;i++) {
      ffx[i] = 0.0;
      ffy[i] = 0.0;
      ffz[i] = 0.0;
    }

    regProximity();
    for(i=0;i<Nmt;i++) {
      fpi = dFdroh(i);
      for(k=1;k<reg[i][0];k++) {
        j = reg[i][k];
        if (j>i) {
          xi = xx[i]; xj = xx[j]; yi = yy[i]; yj = yy[j]; zi = zz[i]; zj = zz[j];
          if (xi-xj>0.5*xMax) { xj += xMax; };
          if (xi-xj<-0.5*xMax) { xj -= xMax; };
          if (yi-yj>0.5*yMax) { yj += yMax; };
          if (yi-yj<-0.5*yMax) { yj -= yMax; };
          if (zi-zj>0.5*zMax) { zj += zMax; };
          if (zi-zj<-0.5*zMax) { zj -= zMax; }; 

          rij = rijReg[i][k];
          f = force(rij,fpi,kind[i],kind[j]);
          fxij = f*(xi-xj)/rij;
          fyij = f*(yi-yj)/rij;
          fzij = f*(zi-zj)/rij;

          ffx[i] +=  fxij;
          ffy[i] +=  fyij;
          ffz[i] +=  fzij;

          ffx[j] += -fxij;
          ffy[j] += -fyij;
          ffz[j] += -fzij;
        }
      }
    }

  }

/*--------------------  registration of near atoms   ---*/

  void regNear() {
    int i,j,k;
    double xi,xj,yi,yj,zi,zj;
    double rrg,rrg2,r2;

    rrg = rcutoff;
    rrg += 3000.0*dt*10;
    rrg2 = rrg*rrg;

    for(i=0;i<Nmt;i++) {
      k = 1;
      for(j=0;j<Nmt;j++) {
        if (i!=j) {
          xi = xx[i]; xj = xx[j]; yi = yy[i]; yj = yy[j]; zi = zz[i]; zj = zz[j];
          if (xi-xj>0.5*xMax) { xj += xMax; };
          if (xi-xj<-0.5*xMax) { xj -= xMax; };
          if (yi-yj>0.5*yMax) { yj += yMax; };
          if (yi-yj<-0.5*yMax) { yj -= yMax; };
          if (zi-zj>0.5*zMax) { zj += zMax; };
          if (zi-zj<-0.5*zMax) { zj -= zMax; }; 
          r2=(xi-xj)*(xi-xj)+(yi-yj)*(yi-yj)+(zi-zj)*(zi-zj);
          if (r2<rrg2) {
            regNr[i][k]=j;
            k += 1;
          }
        }
      }
      regNr[i][0]=k;
    }

  }

/*--------------------  Sutton-Chen Potential Calculation   ---*/

  double force(double r,double fpi,int ki, int kj) { 
    double ra,rt;

    ra = r*1.0e10;

    rt = -RTSeps[ki][kj]*dpotVdr(ra,ki,kj)+2.0*RTSeps[ki][kj]*fpi*SuttonChen[ki][4]*dfaidr(ra,ki,kj);
    return ( rt*1.6e-19/1.0e-10 );
  }

  void regProximity() {
    int i,j,k,jj;
    double xi,xj,yi,yj,zi,zj;
    double rrg,rrg2,r2;

    rrg = rcutoff;
    rrg2 = rrg*rrg;

    for(i=0;i<Nmt;i++) {
      k = 1;
      for(jj=1;jj<regNr[i][0];jj++) {
        j = regNr[i][jj];
        xi = xx[i]; xj = xx[j]; yi = yy[i]; yj = yy[j]; zi = zz[i]; zj = zz[j];
        if (xi-xj>0.5*xMax) { xj += xMax; };
        if (xi-xj<-0.5*xMax) { xj -= xMax; };
        if (yi-yj>0.5*yMax) { yj += yMax; };
        if (yi-yj<-0.5*yMax) { yj -= yMax; };
        if (zi-zj>0.5*zMax) { zj += zMax; };
        if (zi-zj<-0.5*zMax) { zj -= zMax; }; 
        r2=(xi-xj)*(xi-xj)+(yi-yj)*(yi-yj)+(zi-zj)*(zi-zj);
        if (r2<rrg2) {
          reg[i][k]=j;
          rijReg[i][k] = Math.sqrt(r2);
          k += 1;
        }
      }
      reg[i][0]=k;
    }

  }

  double dFdroh(int i) {
    double rh,ret;

    rh = roh(i);
    ret = 0.0;
    if (rh>0.0) { 
      ret = 0.5*Math.sqrt(1.0/rh);
    }
    return ( ret );
  }


  double roh(int i) {
    int j,k;
    double s,ra;

    s = 0.0;
    for(k=1;k<reg[i][0];k++) {
      j = reg[i][k];
      s += fai(rijReg[i][k]*1.0e10,kind[i],kind[j]);
    }

    return(s);
  }

  double fai(double ra, int ki, int kj) {
    return (  Math.pow(RTSa[ki][kj]/ra,RTSm[ki][kj]) );
  }

  double dfaidr(double ra,int ki, int kj) {
    return ( -RTSm[ki][kj]*Math.pow(RTSa[ki][kj]/ra,RTSm[ki][kj])/ra );
  }


  double potV(double ra, int ki, int kj) {
    return ( Math.pow(RTSa[ki][kj]/ra,RTSn[ki][kj]) );
  }

  double dpotVdr(double ra, int ki, int kj) {
    return ( -RTSn[ki][kj]*Math.pow(RTSa[ki][kj]/ra,RTSn[ki][kj])/ra );
  }

/*----- end of molecules motion -----*/

}  

/*----- end of applet -----*/