void PairLJCutalpha::compute(int eflag, int vflag)
{
  int i,j,ii,jj,inum,jnum,itype,jtype;
  double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
  double rsq,r2inv,r6inv,forcelj,factor_lj;
  int *ilist,*jlist,*numneigh,**firstneigh;

  evdwl = 0.0;
  ev_init(eflag,vflag);

  double **x = atom->x;
  double **f = atom->f;
  int *type = atom->type;
  int nlocal = atom->nlocal;
  double *special_lj = force->special_lj;
  int newton_pair = force->newton_pair;

  inum = list->inum;
  ilist = list->ilist;
  numneigh = list->numneigh;
  firstneigh = list->firstneigh;

  // loop over neighbors of my atoms

  for (ii = 0; ii < inum; ii++) {
    i = ilist[ii];
    xtmp = x[i][0];
    ytmp = x[i][1];
    ztmp = x[i][2];
    itype = type[i];
    jlist = firstneigh[i];
    jnum = numneigh[i];

    for (jj = 0; jj < jnum; jj++) {
      j = jlist[jj];
      factor_lj = special_lj[sbmask(j)];
      j &= NEIGHMASK;

      delx = xtmp - x[j][0];
      dely = ytmp - x[j][1];
      delz = ztmp - x[j][2];
      rsq = delx*delx + dely*dely + delz*delz;
      jtype = type[j];

      if (rsq < cutsq[itype][jtype]) {
        r2inv = 1.0/rsq;
        r6inv = r2inv*r2inv*r2inv;
        forcelj = r6inv * (lj1[itype][jtype]*r6inv - lj2[itype][jtype]);
        fpair = factor_lj*forcelj*r2inv;
        
        f[i][0] += delx*fpair;
        f[i][1] += dely*fpair;
        f[i][2] += delz*fpair;
        if (newton_pair || j < nlocal) {
          f[j][0] -= delx*fpair;
          f[j][1] -= dely*fpair;
          f[j][2] -= delz*fpair;
        }

        if (eflag) {
          evdwl = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]) -
            offset[itype][jtype]-1.0*epsilon[itype][jtype];
          evdwl *= factor_lj;
        }

        if (evflag) ev_tally(i,j,nlocal,newton_pair,
                             evdwl,0.0,fpair,delx,dely,delz);
      
      
      } else if (rsq < FACT*cutsq[itype][jtype]) {
        forcelj=epsilon[itype][jtype]*1.0*GAMMA/sigma[itype][jtype]/sigma[itype][jtype]*
                sin(GAMMA/sigma[itype][jtype]/sigma[itype][jtype]*rsq+BETA);
        fpair=factor_lj*forcelj;
      
        f[i][0] += delx*fpair;
        f[i][1] += dely*fpair;
        f[i][2] += delz*fpair;
        if (newton_pair || j < nlocal) {
          f[j][0] -= delx*fpair;
          f[j][1] -= dely*fpair;
          f[j][2] -= delz*fpair;
        }

        if (eflag) {
          evdwl = 0.5*epsilon[itype][jtype]*1.0*
                  (cos(GAMMA*rsq/sigma[itype][jtype]/sigma[itype][jtype]+BETA)-1.0); //!!!modificato qui
          evdwl *= factor_lj;
        }

        if (evflag) ev_tally(i,j,nlocal,newton_pair,
                             evdwl,0.0,fpair,delx,dely,delz);
      
      }
    }
  }

  if (vflag_fdotr) virial_fdotr_compute();
}


////////////////////////////////////////////////
////////////////////////////////////////////////
////////////////////////////////////////////////

void BondFENEalpha::compute(int eflag, int vflag)
{
  int i1,i2,n,type;
  double delx,dely,delz,ebond,fbond;
  double rsq,r0sq,rlogarg,sr2,sr6,sf;

  ebond = sr6 = 0.0;
  ev_init(eflag,vflag);

  double **x = atom->x;
  double **f = atom->f;
  int **bondlist = neighbor->bondlist;
  int nbondlist = neighbor->nbondlist;
  int nlocal = atom->nlocal;
  int newton_bond = force->newton_bond;

  for (n = 0; n < nbondlist; n++) {
    i1 = bondlist[n][0];
    i2 = bondlist[n][1];
    type = bondlist[n][2];

    delx = x[i1][0] - x[i2][0];
    dely = x[i1][1] - x[i2][1];
    delz = x[i1][2] - x[i2][2];

    ///////////////////////
    // force from log term
    ///////////////////////

    rsq = delx*delx + dely*dely + delz*delz;
    r0sq = r0[type] * r0[type];
    rlogarg = 1.0 - rsq/r0sq;

    // if r -> r0, then rlogarg < 0.0 which is an error
    // issue a warning and reset rlogarg = epsilon
    // if r > 2*r0 something serious is wrong, abort

    if (rlogarg < 0.1) {
      char str[128];
      sprintf(str,"FENE bond too long: " BIGINT_FORMAT " "
              TAGINT_FORMAT " " TAGINT_FORMAT " %g",
              update->ntimestep,atom->tag[i1],atom->tag[i2],sqrt(rsq));
      error->warning(FLERR,str,0);
      if (rlogarg <= -3.0) error->one(FLERR,"Bad FENE bond");
      rlogarg = 0.1;
    }

    fbond = -k[type]/rlogarg;

    //////////////////////
    // force from LJ term
    //////////////////////

    if (rsq < TWO_1_3*sigma[type]*sigma[type]) {
      sr2 = sigma[type]*sigma[type]/rsq;
      sr6 = sr2*sr2*sr2;
      //fbond += 48.0*epsilon[type]*sr6*(sr6-0.5)/rsq;
      fbond += 48.0*1.0*sr6*(sr6-0.5)/rsq;
    }
    
    /////////////////////////
    // force from ALPHA term
    /////////////////////////
    
 
    if ((rsq < r0sq*sigma[type]*sigma[type]) && (rsq > TWO_1_3*sigma[type]*sigma[type])) {
    //if (rsq < r0sq*sigma[type]*sigma[type]) {
      //sf = alpha*epsilon[type]*GAMMA/sigma[type]/sigma[type]*sin(GAMMA/sigma[type]/sigma[type]*rsq+BETA);
      sf = epsilon[type]*1.0*GAMMA/sigma[type]/sigma[type]*sin(GAMMA/sigma[type]/sigma[type]*rsq+BETA);
      fbond += sf;
    }
    

    // energy

    if (eflag) {
      ebond = -0.5 * k[type]*r0sq*log(rlogarg);
      if (rsq < TWO_1_3*sigma[type]*sigma[type]) {
        //ebond += 4.0*epsilon[type]*sr6*(sr6-1.0) + epsilon[type]-epsilon[type]*alpha;
        ebond += 4.0*1.0*sr6*(sr6-1.0) + 1.0-1.0*epsilon[type];
      } else if (rsq < r0sq*sigma[type]*sigma[type]) {
        //ebond += 0.5*alpha*epsilon[type]*(cos(GAMMA*rsq/sigma[type]/sigma[type]+BETA)-1.0);
        ebond += 0.5*epsilon[type]*1.0*(cos(GAMMA*rsq/sigma[type]/sigma[type]+BETA)-1.0);
      }
    } 

    // apply force to each of 2 atoms

    if (newton_bond || i1 < nlocal) {
      f[i1][0] += delx*fbond;
      f[i1][1] += dely*fbond;
      f[i1][2] += delz*fbond;
    }

    if (newton_bond || i2 < nlocal) {
      f[i2][0] -= delx*fbond;
      f[i2][1] -= dely*fbond;
      f[i2][2] -= delz*fbond;
    }

    if (evflag) ev_tally(i1,i2,nlocal,newton_bond,ebond,fbond,delx,dely,delz);
  }
}