anchor.diff:    write(*,*) 'mass', mass 
     call main%tic()
     sampling = .false.
  +  enzyme_bound = .false.
  +
     do i = 0, N_loop+equilibration_loops
        if (i==equilibration_loops) sampling = .true.
        if (modulo(i,20) == 0) write(*,'(i05)',advance='no') i
  
positive.code: 
    end function fprime
  
  end program three_bead_enzyme
  
negative.code:         v_com = 0
          !$omp parallel do private(k) reduction(+:kin_e) reduction(+:v_com)
          do k = 1, solvent%Nmax
             if (solvent%species(k)>0) then
                kin_e = kin_e + sum(solvent%vel(:,k)**2) / 2
                v_com = v_com + solvent%vel(:,k)
             end if
          end do
          do k = 1, colloids%Nmax
             v_com = v_com + colloids%mass(colloids%species(k)) * colloids%vel(:,k)
  