+ subroutine Econstr_back
+c MD with umbrella_sampling using Wolyne's distance measure as a constraint
+ implicit real*8 (a-h,o-z)
+ include 'DIMENSIONS'
+ include 'COMMON.CONTROL'
+ include 'COMMON.VAR'
+ include 'COMMON.MD'
+#ifndef LANG0
+ include 'COMMON.LANGEVIN'
+#else
+ include 'COMMON.LANGEVIN.lang0'
+#endif
+ include 'COMMON.CHAIN'
+ include 'COMMON.DERIV'
+ include 'COMMON.GEO'
+ include 'COMMON.LOCAL'
+ include 'COMMON.INTERACT'
+ include 'COMMON.IOUNITS'
+ include 'COMMON.NAMES'
+ include 'COMMON.TIME1'
+ Uconst_back=0.0d0
+ do i=1,nres
+ dutheta(i)=0.0d0
+ dugamma(i)=0.0d0
+ do j=1,3
+ duscdiff(j,i)=0.0d0
+ duscdiffx(j,i)=0.0d0
+ enddo
+ enddo
+ do i=1,nfrag_back
+ ii = ifrag_back(2,i,iset)-ifrag_back(1,i,iset)
+c
+c Deviations from theta angles
+c
+ utheta_i=0.0d0
+ do j=ifrag_back(1,i,iset)+2,ifrag_back(2,i,iset)
+ dtheta_i=theta(j)-thetaref(j)
+ utheta_i=utheta_i+0.5d0*dtheta_i*dtheta_i
+ dutheta(j-2)=dutheta(j-2)+wfrag_back(1,i,iset)*dtheta_i/(ii-1)
+ enddo
+ utheta(i)=utheta_i/(ii-1)
+c
+c Deviations from gamma angles
+c
+ ugamma_i=0.0d0
+ do j=ifrag_back(1,i,iset)+3,ifrag_back(2,i,iset)
+ dgamma_i=pinorm(phi(j)-phiref(j))
+c write (iout,*) j,phi(j),phi(j)-phiref(j)
+ ugamma_i=ugamma_i+0.5d0*dgamma_i*dgamma_i
+ dugamma(j-3)=dugamma(j-3)+wfrag_back(2,i,iset)*dgamma_i/(ii-2)
+c write (iout,*) i,j,dgamma_i,wfrag_back(2,i,iset),dugamma(j-3)
+ enddo
+ ugamma(i)=ugamma_i/(ii-2)
+c
+c Deviations from local SC geometry
+c
+ uscdiff(i)=0.0d0
+ do j=ifrag_back(1,i,iset)+1,ifrag_back(2,i,iset)-1
+ dxx=xxtab(j)-xxref(j)
+ dyy=yytab(j)-yyref(j)
+ dzz=zztab(j)-zzref(j)
+ uscdiff(i)=uscdiff(i)+dxx*dxx+dyy*dyy+dzz*dzz
+ do k=1,3
+ duscdiff(k,j-1)=duscdiff(k,j-1)+wfrag_back(3,i,iset)*
+ & (dXX_C1tab(k,j)*dxx+dYY_C1tab(k,j)*dyy+dZZ_C1tab(k,j)*dzz)/
+ & (ii-1)
+ duscdiff(k,j)=duscdiff(k,j)+wfrag_back(3,i,iset)*
+ & (dXX_Ctab(k,j)*dxx+dYY_Ctab(k,j)*dyy+dZZ_Ctab(k,j)*dzz)/
+ & (ii-1)
+ duscdiffx(k,j)=duscdiffx(k,j)+wfrag_back(3,i,iset)*
+ & (dXX_XYZtab(k,j)*dxx+dYY_XYZtab(k,j)*dyy+dZZ_XYZtab(k,j)*dzz)
+ & /(ii-1)
+ enddo
+c write (iout,'(i5,6f10.5)') j,xxtab(j),yytab(j),zztab(j),
+c & xxref(j),yyref(j),zzref(j)
+ enddo
+ uscdiff(i)=0.5d0*uscdiff(i)/(ii-1)
+c write (iout,*) i," uscdiff",uscdiff(i)
+c
+c Put together deviations from local geometry
+c
+ Uconst_back=Uconst_back+wfrag_back(1,i,iset)*utheta(i)+
+ & wfrag_back(2,i,iset)*ugamma(i)+wfrag_back(3,i,iset)*uscdiff(i)
+c write(iout,*) "i",i," utheta",utheta(i)," ugamma",ugamma(i),
+c & " uconst_back",uconst_back
+ utheta(i)=dsqrt(utheta(i))
+ ugamma(i)=dsqrt(ugamma(i))
+ uscdiff(i)=dsqrt(uscdiff(i))
+ enddo
+ return
+ end