+ t_3dvec dist;
+ double d;
+ int s;
+ t_pcc *pcc;
+
+ /* only count pairs once,
+ * skip same atoms */
+ if(itom->tag>=jtom->tag)
+ return 0;
+
+ /*
+ * pair correlation calc
+ */
+
+ /* get pcc data */
+ pcc=data;
+
+ /* distance */
+ v3_sub(&dist,&(jtom->r),&(itom->r));
+ if(bc) check_per_bound(moldyn,&dist);
+ d=v3_absolute_square(&dist);
+
+ /* ignore if greater cutoff */
+ if(d>moldyn->cutoff_square)
+ return 0;
+
+ /* fill the slots */
+ d=sqrt(d);
+ s=(int)(d/pcc->dr);
+
+ /* should never happen but it does 8) -
+ * related to -ffloat-store problem! */
+ if(s>=pcc->o1) {
+ printf("[moldyn] WARNING: pcc (%d/%d)",
+ s,pcc->o1);
+ printf("\n");
+ s=pcc->o1-1;
+ }
+
+ if(itom->brand!=jtom->brand) {
+ /* mixed */
+ pcc->stat[s]+=1;
+ }
+ else {
+ /* type a - type a bonds */
+ if(itom->brand==0)
+ pcc->stat[s+pcc->o1]+=1;
+ else
+ /* type b - type b bonds */
+ pcc->stat[s+pcc->o2]+=1;
+ }
+
+ return 0;
+}
+
+int calculate_pair_correlation(t_moldyn *moldyn,double dr,void *ptr) {
+
+ t_pcc pcc;
+ double norm;
+ int i;
+
+ pcc.dr=dr;
+ pcc.o1=moldyn->cutoff/dr;
+ pcc.o2=2*pcc.o1;
+
+ if(pcc.o1*dr<=moldyn->cutoff)
+ printf("[moldyn] WARNING: pcc (low #slots)\n");
+
+ printf("[moldyn] pair correlation calc info:\n");
+ printf(" time: %f\n",moldyn->time);
+ printf(" count: %d\n",moldyn->count);
+ printf(" cutoff: %f\n",moldyn->cutoff);
+ printf(" temperature: cur=%f avg=%f\n",moldyn->t,moldyn->t_avg);
+
+ if(ptr!=NULL) {
+ pcc.stat=(double *)ptr;
+ }
+ else {
+ pcc.stat=(double *)malloc(3*pcc.o1*sizeof(double));
+ if(pcc.stat==NULL) {
+ perror("[moldyn] pair correlation malloc");
+ return -1;
+ }
+ }
+
+ memset(pcc.stat,0,3*pcc.o1*sizeof(double));
+
+ /* process */
+ process_2b_bonds(moldyn,&pcc,calculate_pair_correlation_process);
+
+ /* normalization */
+ for(i=1;i<pcc.o1;i++) {
+ // normalization: 4 pi r^2 dr
+ // here: not double counting pairs -> 2 pi r r dr
+ // ... and actually it's a constant times r^2
+ norm=i*i*dr*dr;
+ pcc.stat[i]/=norm;
+ pcc.stat[pcc.o1+i]/=norm;
+ pcc.stat[pcc.o2+i]/=norm;
+ }
+ /* */
+
+ if(ptr==NULL) {
+ /* todo: store/print pair correlation function */
+ free(pcc.stat);
+ }
+
+ return 0;
+}
+
+int bond_analyze_process(t_moldyn *moldyn,t_atom *itom,t_atom *jtom,
+ void *data,u8 bc) {
+
+ t_ba *ba;
+ t_3dvec dist;
+ double d;
+
+ if(itom->tag>=jtom->tag)
+ return 0;
+
+ /* distance */
+ v3_sub(&dist,&(jtom->r),&(itom->r));
+ if(bc) check_per_bound(moldyn,&dist);
+ d=v3_absolute_square(&dist);
+
+ /* ignore if greater or equal cutoff */
+ if(d>moldyn->cutoff_square)
+ return 0;
+
+ /* check for potential bond */
+ if(moldyn->check_2b_bond(moldyn,itom,jtom,bc)==FALSE)
+ return 0;
+
+ /* now count this bonding ... */
+ ba=data;
+
+ /* increase total bond counter
+ */
+ ba->tcnt+=1;
+
+ if(itom->brand==0)
+ ba->acnt[jtom->tag]+=1;
+ else
+ ba->bcnt[jtom->tag]+=1;