anchor.diff:          ix=Lx(i);iy=Ly(i);iz=Lz(i)
           ixt=-ix;iyt=iy;izt=iz
           ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
  -        itable_sym(1,i)=Lxyz(ixt,iyt,izt)
  +        itable_sym(1,Lxyz(ixt,iyt,izt))=i
         end do
   ! (x,y,z) -> (x,-y,z)
         do i=1,NL
           ix=Lx(i);iy=Ly(i);iz=Lz(i)
           ixt=ix;iyt=-iy;izt=iz
           ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
  -        itable_sym(2,i)=Lxyz(ixt,iyt,izt)
  +        itable_sym(2,Lxyz(ixt,iyt,izt))=i
         end do
   ! (x,y,z) -> (x+aLx/2,y+aLy/2,z+aLz/2)
         do i=1,NL
           ix=Lx(i);iy=Ly(i);iz=Lz(i)
           ixt=ix+NLx/2;iyt=iy+NLy/2;izt=iz+NLz/2
           ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
  -        itable_sym(3,i)=Lxyz(ixt,iyt,izt)
  +        itable_sym(3,Lxyz(ixt,iyt,izt))=i
       end do
   ! (x,y,z) -> (y,-x+aLx/2,z+aLz/4)
         do i=1,NL
           ix=Lx(i);iy=Ly(i);iz=Lz(i)
           ixt=iy;iyt=-ix+NLx/2;izt=iz+NLz/4
           ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
  -        itable_sym(4,i)=Lxyz(ixt,iyt,izt)
  +        itable_sym(4,Lxyz(ixt,iyt,izt))=i
       end do
   !===  end  diamond2(8) ====================================================================
     else if((Sym == 8).and.(crystal_structure == 'diamond')) then
  
positive.code:     do i=1,NL
        ix=Lx(i);iy=Ly(i);iz=Lz(i)
        ixt=iy;iyt=ix;izt=iz ! R_1
        itable_sym(1,i)=Lxyz(ixt,iyt,izt)
      end do
  ! 2. T_2
      do i=1,NL
        ix=Lx(i);iy=Ly(i);iz=Lz(i)
        ixt=-iy;iyt=-ix;izt=iz
        ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
        itable_sym(2,i)=Lxyz(ixt,iyt,izt)
      end do
  ! 3. T_3
      do i=1,NL
        ix=Lx(i);iy=Ly(i);iz=Lz(i)
        ixt=-iy;iyt=ix;izt=iz ! R_3
        ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
        itable_sym(3,i)=Lxyz(ixt,iyt,izt)
      end do
  ! 4. T_3*T_3
      do i=1,NL
  
negative.code:       ix=ixt;iy=iyt;iz=izt
        ixt=-iy+NLx/4;iyt=ix+NLy/4;izt=iz+NLz/4 ! T_3
        ixt=mod(ixt+2*NLx,NLx);iyt=mod(iyt+2*NLy,NLy);izt=mod(izt+2*NLz,NLz)
        itable_sym(2,Lxyz(ixt,iyt,izt))=i
      end do
  !===  end  diamond(4) ====================================================================
    else if((Sym == 8).and.(crystal_structure == 'tetragonal')) then
  