Esempio n. 1
0
/*! \brief
 * Sets ua a search grid for a given box.
 *
 * \param[in,out] d    Grid information.
 * \param[in]     pbc  Information about the box.
 * \returns  FALSE if grid search is not suitable.
 */
static gmx_bool
grid_set_box(gmx_ana_nbsearch_t *d, t_pbc *pbc)
{
    int dd;

    /* TODO: This check could be improved. */
    if (0.5*pbc->max_cutoff2 < d->cutoff2)
    {
        return FALSE;
    }

    if (!grid_setup_cells(d, pbc))
    {
        return FALSE;
    }

    d->bTric = TRICLINIC(pbc->box);
    if (d->bTric)
    {
        for (dd = 0; dd < DIM; ++dd)
        {
            svmul(1.0 / d->ncelldim[dd], pbc->box[dd], d->cellbox[dd]);
        }
        m_inv_ur0(d->cellbox, d->recipcell);
    }
    else
    {
        for (dd = 0; dd < DIM; ++dd)
        {
            d->cellbox[dd][dd]   = pbc->box[dd][dd] / d->ncelldim[dd];
            d->recipcell[dd][dd] = 1 / d->cellbox[dd][dd];
        }
    }
    grid_init_cell_nblist(d, pbc);
    return TRUE;
}
Esempio n. 2
0
int gmx_vanhove(int argc,char *argv[])
{
  const char *desc[] = {
    "g_vanhove computes the Van Hove correlation function.",
    "The Van Hove G(r,t) is the probability that a particle that is at r0",
    "at time zero can be found at position r0+r at time t.",
    "g_vanhove determines G not for a vector r, but for the length of r.",
    "Thus it gives the probability that a particle moves a distance of r",
    "in time t.",
    "Jumps across the periodic boundaries are removed.",
    "Corrections are made for scaling due to isotropic",
    "or anisotropic pressure coupling.",
    "[PAR]",
    "With option [TT]-om[tt] the whole matrix can be written as a function",
    "of t and r or as a function of sqrt(t) and r (option [TT]-sqrt[tt]).",
    "[PAR]",
    "With option [TT]-or[tt] the Van Hove function is plotted for one",
    "or more values of t. Option [TT]-nr[tt] sets the number of times,",
    "option [TT]-fr[tt] the number spacing between the times.",
    "The binwidth is set with option [TT]-rbin[tt]. The number of bins",
    "is determined automatically.",
    "[PAR]",
    "With option [TT]-ot[tt] the integral up to a certain distance",
    "(option [TT]-rt[tt]) is plotted as a function of time.",
    "[PAR]",
    "For all frames that are read the coordinates of the selected particles",
    "are stored in memory. Therefore the program may use a lot of memory.",
    "For options [TT]-om[tt] and [TT]-ot[tt] the program may be slow.",
    "This is because the calculation scales as the number of frames times",
    "[TT]-fm[tt] or [TT]-ft[tt].",
    "Note that with the [TT]-dt[tt] option the memory usage and calculation",
    "time can be reduced."
  };
  static int fmmax=0,ftmax=0,nlev=81,nr=1,fshift=0;
  static real sbin=0,rmax=2,rbin=0.01,mmax=0,rint=0;
  t_pargs pa[] = {
    { "-sqrt",    FALSE, etREAL,{&sbin},
      "Use sqrt(t) on the matrix axis which binspacing # in sqrt(ps)" },
    { "-fm",      FALSE, etINT, {&fmmax},
      "Number of frames in the matrix, 0 is plot all" },
    { "-rmax",    FALSE, etREAL, {&rmax},
      "Maximum r in the matrix (nm)" },
    { "-rbin",    FALSE, etREAL, {&rbin},
      "Binwidth in the matrix and for -or (nm)" },
    { "-mmax",    FALSE, etREAL, {&mmax},
      "Maximum density in the matrix, 0 is calculate (1/nm)" },
    { "-nlevels" ,FALSE, etINT,  {&nlev}, 
      "Number of levels in the matrix" },
    { "-nr",      FALSE, etINT, {&nr},
      "Number of curves for the -or output" },
    { "-fr",      FALSE, etINT, {&fshift},
      "Frame spacing for the -or output" },
    { "-rt",      FALSE, etREAL, {&rint},
      "Integration limit for the -ot output (nm)" },
    { "-ft",      FALSE, etINT, {&ftmax},
      "Number of frames in the -ot output, 0 is plot all" }
  };
#define NPA asize(pa)

  t_filenm fnm[] = { 
    { efTRX, NULL, NULL,  ffREAD },
    { efTPS, NULL, NULL,  ffREAD }, 
    { efNDX, NULL, NULL,  ffOPTRD },
    { efXPM, "-om", "vanhove", ffOPTWR },
    { efXVG, "-or", "vanhove_r", ffOPTWR },
    { efXVG, "-ot", "vanhove_t", ffOPTWR }
  };
#define NFILE asize(fnm)

  output_env_t oenv;
  const char *matfile,*otfile,*orfile;
  char     title[256];
  t_topology top;
  int      ePBC;
  matrix   boxtop,box,*sbox,avbox,corr;
  rvec     *xtop,*x,**sx;
  int      isize,nalloc,nallocn,natom;
  t_trxstatus *status;
  atom_id  *index;
  char     *grpname;
  int      nfr,f,ff,i,m,mat_nx=0,nbin=0,bin,mbin,fbin;
  real     *time,t,invbin=0,rmax2=0,rint2=0,d2;
  real     invsbin=0,matmax,normfac,dt,*tickx,*ticky;
  char     buf[STRLEN],**legend;
  real     **mat=NULL;
  int      *pt=NULL,**pr=NULL,*mcount=NULL,*tcount=NULL,*rcount=NULL;
  FILE     *fp;
  t_rgb    rlo={1,1,1}, rhi={0,0,0};

  CopyRight(stderr,argv[0]);

  parse_common_args(&argc,argv,PCA_CAN_VIEW | PCA_CAN_TIME | PCA_BE_NICE,
		    NFILE,fnm,asize(pa),pa,asize(desc),desc,0,NULL,&oenv);
  
  matfile = opt2fn_null("-om",NFILE,fnm);
  if (opt2parg_bSet("-fr",NPA,pa))
    orfile  = opt2fn("-or",NFILE,fnm);
  else
    orfile  = opt2fn_null("-or",NFILE,fnm);
  if (opt2parg_bSet("-rt",NPA,pa))
    otfile  = opt2fn("-ot",NFILE,fnm);
  else
    otfile  = opt2fn_null("-ot",NFILE,fnm);
  
  if (!matfile && !otfile && !orfile) {
    fprintf(stderr,
	    "For output set one (or more) of the output file options\n");
    exit(0);
  }
  
  read_tps_conf(ftp2fn(efTPS,NFILE,fnm),title,&top,&ePBC,&xtop,NULL,boxtop,
		FALSE); 
  get_index(&top.atoms,ftp2fn_null(efNDX,NFILE,fnm),1,&isize,&index,&grpname);
  
  nalloc = 0;
  time = NULL;
  sbox = NULL;
  sx   = NULL;
  clear_mat(avbox);

  natom=read_first_x(oenv,&status,ftp2fn(efTRX,NFILE,fnm),&t,&x,box);
  nfr = 0;
  do {
    if (nfr >= nalloc) {
      nalloc += 100;
      srenew(time,nalloc);
      srenew(sbox,nalloc);
      srenew(sx,nalloc);
    }
    
    time[nfr] = t;
    copy_mat(box,sbox[nfr]);
    /* This assumes that the off-diagonal box elements
     * are not affected by jumps across the periodic boundaries.
     */
    m_add(avbox,box,avbox);
    snew(sx[nfr],isize);
    for(i=0; i<isize; i++)
     copy_rvec(x[index[i]],sx[nfr][i]);
    
    nfr++;
  } while (read_next_x(oenv,status,&t,natom,x,box));

  /* clean up */
  sfree(x);
  close_trj(status);
  
  fprintf(stderr,"Read %d frames\n",nfr);

  dt = (time[nfr-1] - time[0])/(nfr - 1);
  /* Some ugly rounding to get nice nice times in the output */
  dt = (int)(10000.0*dt + 0.5)/10000.0;

  invbin = 1.0/rbin;

  if (matfile) {
    if (fmmax <= 0 || fmmax >= nfr)
      fmmax = nfr - 1;
    snew(mcount,fmmax);
    nbin = (int)(rmax*invbin + 0.5);
    if (sbin == 0) {
      mat_nx = fmmax + 1;
    } else {
      invsbin = 1.0/sbin;
      mat_nx = sqrt(fmmax*dt)*invsbin + 1;
    }
    snew(mat,mat_nx);
    for(f=0; f<mat_nx; f++)
      snew(mat[f],nbin);
    rmax2 = sqr(nbin*rbin);
    /* Initialize time zero */
    mat[0][0] = nfr*isize;
    mcount[0] += nfr;
  } else {
    fmmax = 0;
  }
  
  if (orfile) {
    snew(pr,nr);
    nalloc = 0;
    snew(rcount,nr);
  }
  
  if (otfile) {
    if (ftmax <= 0)
      ftmax = nfr - 1;
    snew(tcount,ftmax);
    snew(pt,nfr);
    rint2 = rint*rint;
    /* Initialize time zero */
    pt[0] = nfr*isize;
    tcount[0] += nfr;
  } else {
    ftmax = 0;
  }

  msmul(avbox,1.0/nfr,avbox);
  for(f=0; f<nfr; f++) {
    if (f % 100 == 0)
      fprintf(stderr,"\rProcessing frame %d",f);
    /* Scale all the configuration to the average box */
    m_inv_ur0(sbox[f],corr);
    mmul_ur0(avbox,corr,corr);
    for(i=0; i<isize; i++) {
      mvmul_ur0(corr,sx[f][i],sx[f][i]);
      if (f > 0) {
	/* Correct for periodic jumps */
	for(m=DIM-1; m>=0; m--) {
	  while(sx[f][i][m] - sx[f-1][i][m] > 0.5*avbox[m][m])
	    rvec_dec(sx[f][i],avbox[m]);
	  while(sx[f][i][m] - sx[f-1][i][m] <= -0.5*avbox[m][m])
	    rvec_inc(sx[f][i],avbox[m]);
	}
      }
    }
    for(ff=0; ff<f; ff++) {
      fbin = f - ff;
      if (fbin <= fmmax || fbin <= ftmax) {
	if (sbin == 0)
	  mbin = fbin;
	else
	  mbin = (int)(sqrt(fbin*dt)*invsbin + 0.5);
	for(i=0; i<isize; i++) {
	  d2 = distance2(sx[f][i],sx[ff][i]);
	  if (mbin < mat_nx && d2 < rmax2) {
	    bin = (int)(sqrt(d2)*invbin + 0.5);
	    if (bin < nbin) {
	      mat[mbin][bin] += 1;
	    }
	  }
	  if (fbin <= ftmax && d2 <= rint2)
	    pt[fbin]++;
	}
	if (matfile)
	  mcount[mbin]++;
	if (otfile)
	  tcount[fbin]++;
      }
    }
    if (orfile) {
      for(fbin=0; fbin<nr; fbin++) {
	ff = f - (fbin + 1)*fshift;
	if (ff >= 0) {
	  for(i=0; i<isize; i++) {
	    d2 = distance2(sx[f][i],sx[ff][i]);
	    bin = (int)(sqrt(d2)*invbin);
	    if (bin >= nalloc) {
	      nallocn = 10*(bin/10) + 11;
	      for(m=0; m<nr; m++) {
		srenew(pr[m],nallocn);
		for(i=nalloc; i<nallocn; i++)
		  pr[m][i] = 0;
	      }
	      nalloc = nallocn;
	    }
	    pr[fbin][bin]++;
	  }
	  rcount[fbin]++;
	}
      }
    }
  }
  fprintf(stderr,"\n");
  
  if (matfile) {
    matmax = 0;
    for(f=0; f<mat_nx; f++) {
      normfac = 1.0/(mcount[f]*isize*rbin);
      for(i=0; i<nbin; i++) {
	mat[f][i] *= normfac;
	if (mat[f][i] > matmax && (f!=0 || i!=0))
	  matmax = mat[f][i];
      }
    }
    fprintf(stdout,"Value at (0,0): %.3f, maximum of the rest %.3f\n",
	    mat[0][0],matmax);
    if (mmax > 0)
      matmax = mmax;
    snew(tickx,mat_nx);
    for(f=0; f<mat_nx; f++) {
      if (sbin == 0)
	tickx[f] = f*dt;
      else
	tickx[f] = f*sbin;
    }
    snew(ticky,nbin+1);
    for(i=0; i<=nbin; i++)
      ticky[i] = i*rbin;
    fp = ffopen(matfile,"w");
    write_xpm(fp,MAT_SPATIAL_Y,"Van Hove function","G (1/nm)",
	      sbin==0 ? "time (ps)" : "sqrt(time) (ps^1/2)","r (nm)",
	      mat_nx,nbin,tickx,ticky,mat,0,matmax,rlo,rhi,&nlev);     
    ffclose(fp);
  }
  
  if (orfile) {
    fp = xvgropen(orfile,"Van Hove function","r (nm)","G (nm\\S-1\\N)",oenv);
    fprintf(fp,"@ subtitle \"for particles in group %s\"\n",grpname);
    snew(legend,nr);
    for(fbin=0; fbin<nr; fbin++) {
      sprintf(buf,"%g ps",(fbin + 1)*fshift*dt);
      legend[fbin] = strdup(buf);
    }
    xvgr_legend(fp,nr,(const char**)legend,oenv);
    for(i=0; i<nalloc; i++) {
      fprintf(fp,"%g",i*rbin);
      for(fbin=0; fbin<nr; fbin++)
	fprintf(fp," %g",
		(real)pr[fbin][i]/(rcount[fbin]*isize*rbin*(i==0 ? 0.5 : 1)));
      fprintf(fp,"\n");
    }
    ffclose(fp);
  }
  
  if (otfile) {
    sprintf(buf,"Probability of moving less than %g nm",rint);
    fp = xvgropen(otfile,buf,"t (ps)","",oenv);
    fprintf(fp,"@ subtitle \"for particles in group %s\"\n",grpname);
    for(f=0; f<=ftmax; f++)
      fprintf(fp,"%g %g\n",f*dt,(real)pt[f]/(tcount[f]*isize));
    ffclose(fp);
  }

  do_view(oenv, matfile,NULL);
  do_view(oenv, orfile,NULL);
  do_view(oenv, otfile,NULL);

  thanx(stderr);
  
  return 0;
}
Esempio n. 3
0
void parrinellorahman_pcoupl(FILE *fplog,gmx_step_t step,
			     t_inputrec *ir,real dt,tensor pres,
			     tensor box,tensor box_rel,tensor boxv,
			     tensor M,matrix mu,bool bFirstStep)
{
  /* This doesn't do any coordinate updating. It just
   * integrates the box vector equations from the calculated
   * acceleration due to pressure difference. We also compute
   * the tensor M which is used in update to couple the particle
   * coordinates to the box vectors.
   *
   * In Nose and Klein (Mol.Phys 50 (1983) no 5., p 1055) this is
   * given as
   *            -1    .           .     -1
   * M_nk = (h')   * (h' * h + h' h) * h
   *
   * with the dots denoting time derivatives and h is the transformation from
   * the scaled frame to the real frame, i.e. the TRANSPOSE of the box. 
   * This also goes for the pressure and M tensors - they are transposed relative
   * to ours. Our equation thus becomes:
   *
   *                  -1       .    .           -1
   * M_gmx = M_nk' = b  * (b * b' + b * b') * b'
   * 
   * where b is the gromacs box matrix.                       
   * Our box accelerations are given by
   *   ..                                    ..
   *   b = vol/W inv(box') * (P-ref_P)     (=h')
   */
  
  int    d,n;
  tensor winv;
  real   vol=box[XX][XX]*box[YY][YY]*box[ZZ][ZZ];
  real   atot,arel,change,maxchange,xy_pressure;
  tensor invbox,pdiff,t1,t2;

  real maxl;

  m_inv_ur0(box,invbox);

  if (!bFirstStep) {
    /* Note that PRESFAC does not occur here.
     * The pressure and compressibility always occur as a product,
     * therefore the pressure unit drops out.
     */
    maxl=max(box[XX][XX],box[YY][YY]);
    maxl=max(maxl,box[ZZ][ZZ]);
    for(d=0;d<DIM;d++)
      for(n=0;n<DIM;n++)
	winv[d][n]=
	  (4*M_PI*M_PI*ir->compress[d][n])/(3*ir->tau_p*ir->tau_p*maxl);
    
    m_sub(pres,ir->ref_p,pdiff);
    
    if(ir->epct==epctSURFACETENSION) {
      /* Unlike Berendsen coupling it might not be trivial to include a z
       * pressure correction here? On the other hand we don't scale the
       * box momentarily, but change accelerations, so it might not be crucial.
       */
      xy_pressure=0.5*(pres[XX][XX]+pres[YY][YY]);
      for(d=0;d<ZZ;d++)
	pdiff[d][d]=(xy_pressure-(pres[ZZ][ZZ]-ir->ref_p[d][d]/box[d][d]));
    }
    
    tmmul(invbox,pdiff,t1);
    /* Move the off-diagonal elements of the 'force' to one side to ensure
     * that we obey the box constraints.
     */
    for(d=0;d<DIM;d++) {
      for(n=0;n<d;n++) {
	t1[d][n] += t1[n][d];
	t1[n][d] = 0;
      }
    }
    
    switch (ir->epct) {
    case epctANISOTROPIC:
      for(d=0;d<DIM;d++) 
	for(n=0;n<=d;n++)
	  t1[d][n] *= winv[d][n]*vol;
      break;
    case epctISOTROPIC:
      /* calculate total volume acceleration */
      atot=box[XX][XX]*box[YY][YY]*t1[ZZ][ZZ]+
	box[XX][XX]*t1[YY][YY]*box[ZZ][ZZ]+
	t1[XX][XX]*box[YY][YY]*box[ZZ][ZZ];
      arel=atot/(3*vol);
      /* set all RELATIVE box accelerations equal, and maintain total V
       * change speed */
      for(d=0;d<DIM;d++)
	for(n=0;n<=d;n++)
	  t1[d][n] = winv[0][0]*vol*arel*box[d][n];    
      break;
    case epctSEMIISOTROPIC:
    case epctSURFACETENSION:
      /* Note the correction to pdiff above for surftens. coupling  */
      
      /* calculate total XY volume acceleration */
      atot=box[XX][XX]*t1[YY][YY]+t1[XX][XX]*box[YY][YY];
      arel=atot/(2*box[XX][XX]*box[YY][YY]);
      /* set RELATIVE XY box accelerations equal, and maintain total V
       * change speed. Dont change the third box vector accelerations */
      for(d=0;d<ZZ;d++)
	for(n=0;n<=d;n++)
	  t1[d][n] = winv[d][n]*vol*arel*box[d][n];
      for(n=0;n<DIM;n++)
	t1[ZZ][n] *= winv[d][n]*vol;
      break;
    default:
      gmx_fatal(FARGS,"Parrinello-Rahman pressure coupling type %s "
		  "not supported yet\n",EPCOUPLTYPETYPE(ir->epct));
      break;
    }
    
    maxchange=0;
    for(d=0;d<DIM;d++)
      for(n=0;n<=d;n++) {
	boxv[d][n] += dt*t1[d][n];
	/* We do NOT update the box vectors themselves here, since
	 * we need them for shifting later. It is instead done last
	 * in the update() routine.
	 */
	
	/* Calculate the change relative to diagonal elements -
	 * since it's perfectly ok for the off-diagonal ones to
	 * be zero it doesn't make sense to check the change relative
	 * to its current size.
	 */
	change=fabs(dt*boxv[d][n]/box[d][d]);
	if(change>maxchange)
	  maxchange=change;
      }
    
    if (maxchange > 0.01 && fplog) {
      char buf[22];
      fprintf(fplog,"\nStep %s  Warning: Pressure scaling more than 1%%.\n",
	      gmx_step_str(step,buf));
    }
  }
  
  preserve_box_shape(ir,box_rel,boxv);

  mtmul(boxv,box,t1);       /* t1=boxv * b' */
  mmul(invbox,t1,t2);
  mtmul(t2,invbox,M);

  /* Determine the scaling matrix mu for the coordinates */
  for(d=0;d<DIM;d++)
    for(n=0;n<=d;n++)
      t1[d][n] = box[d][n] + dt*boxv[d][n];
  preserve_box_shape(ir,box_rel,t1);
  /* t1 is the box at t+dt, determine mu as the relative change */
  mmul_ur0(invbox,t1,mu);
}
Esempio n. 4
0
static void read_posres(gmx_mtop_t *mtop,t_molinfo *molinfo,bool bTopB,
			char *fn,
			int rc_scaling, int ePBC, 
			rvec com)
{
  bool   bFirst = TRUE;
  rvec   *x,*v,*xp;
  dvec   sum;
  double totmass;
  t_atoms dumat;
  matrix box,invbox;
  int    natoms,npbcdim=0;
  char   title[STRLEN];
  int    a,i,ai,j,k,mb,nat_molb;
  gmx_molblock_t *molb;
  t_params *pr;
  t_atom *atom;

  get_stx_coordnum(fn,&natoms);
  if (natoms != mtop->natoms) {
    sprintf(warn_buf,"The number of atoms in %s (%d) does not match the number of atoms in the topology (%d). Will assume that the first %d atoms in the topology and %s match.",fn,natoms,mtop->natoms,min(mtop->natoms,natoms),fn);
    warning(NULL);
  }
  snew(x,natoms);
  snew(v,natoms);
  init_t_atoms(&dumat,natoms,FALSE);
  read_stx_conf(fn,title,&dumat,x,v,NULL,box);
  
  npbcdim = ePBC2npbcdim(ePBC);
  clear_rvec(com);
  if (rc_scaling != erscNO) {
    copy_mat(box,invbox);
    for(j=npbcdim; j<DIM; j++) {
      clear_rvec(invbox[j]);
      invbox[j][j] = 1;
    }
    m_inv_ur0(invbox,invbox);
  }

  /* Copy the reference coordinates to mtop */
  clear_dvec(sum);
  totmass = 0;
  a = 0;
  for(mb=0; mb<mtop->nmolblock; mb++) {
    molb = &mtop->molblock[mb];
    nat_molb = molb->nmol*mtop->moltype[molb->type].atoms.nr;
    pr = &(molinfo[molb->type].plist[F_POSRES]);
    if (pr->nr > 0) {
      atom = mtop->moltype[molb->type].atoms.atom;
      for(i=0; (i<pr->nr); i++) {
	ai=pr->param[i].AI;
	if (ai >= natoms) {
	  gmx_fatal(FARGS,"Position restraint atom index (%d) in moltype '%s' is larger than number of atoms in %s (%d).\n",
		    ai+1,*molinfo[molb->type].name,fn,natoms);
	}
	if (rc_scaling == erscCOM) {
	  /* Determine the center of mass of the posres reference coordinates */
	  for(j=0; j<npbcdim; j++) {
	    sum[j] += atom[ai].m*x[a+ai][j];
	  }
	  totmass  += atom[ai].m;
	}
      }
      if (!bTopB) {
	molb->nposres_xA = nat_molb;
	snew(molb->posres_xA,molb->nposres_xA);
	for(i=0; i<nat_molb; i++) {
	  copy_rvec(x[a+i],molb->posres_xA[i]);
	}
      } else {
	molb->nposres_xB = nat_molb;
	snew(molb->posres_xB,molb->nposres_xB);
	for(i=0; i<nat_molb; i++) {
	  copy_rvec(x[a+i],molb->posres_xB[i]);
	}
      }
    }
    a += nat_molb;
  }
  if (rc_scaling == erscCOM) {
    if (totmass == 0)
      gmx_fatal(FARGS,"The total mass of the position restraint atoms is 0");
    for(j=0; j<npbcdim; j++)
      com[j] = sum[j]/totmass;
    fprintf(stderr,"The center of mass of the position restraint coord's is %6.3f %6.3f %6.3f\n",com[XX],com[YY],com[ZZ]);
  }

  if (rc_scaling != erscNO) {
    for(mb=0; mb<mtop->nmolblock; mb++) {
      molb = &mtop->molblock[mb];
      nat_molb = molb->nmol*mtop->moltype[molb->type].atoms.nr;
      if (molb->nposres_xA > 0 || molb->nposres_xB > 0) {
	xp = (!bTopB ? molb->posres_xA : molb->posres_xB);
	for(i=0; i<nat_molb; i++) {
	  for(j=0; j<npbcdim; j++) {
	    if (rc_scaling == erscALL) {
	      /* Convert from Cartesian to crystal coordinates */
	      xp[i][j] *= invbox[j][j];
	      for(k=j+1; k<npbcdim; k++) {
		xp[i][j] += invbox[k][j]*xp[i][k];
	      }
	    } else if (rc_scaling == erscCOM) {
	      /* Subtract the center of mass */
	      xp[i][j] -= com[j];
	    }
	  }
	}
      }
    }

    if (rc_scaling == erscCOM) {
      /* Convert the COM from Cartesian to crystal coordinates */
      for(j=0; j<npbcdim; j++) {
	com[j] *= invbox[j][j];
	for(k=j+1; k<npbcdim; k++) {
	  com[j] += invbox[k][j]*com[k];
	}
      }
    }
  }
  
  free_t_atoms(&dumat,TRUE);
  sfree(x);
  sfree(v);
}