anchor.diff:  !! \param sigma_E                 radius of enzymatic_site
   !! \param sigma_N                 radius of N sphere
   !! \param link_d                  length of rigid link
  -!! \param link_angle              angle of the model at rest
  +!! \param link_angles             angle of the model at rest
   !! \param elastic_k               stiffness of the link
   !! \param angle_k                 stiffness of the angular link
   !! \param epsilon_C               interaction parameter of C sphere with both solvent species (2 elements)
  
positive.code:     end do
      kin = kin / 2
  
      factor = sqrt((kin + energy)/kin)
      do i = start, start + n - 1
         solvent%vel(:,i) = com_v + factor*(solvent%vel(:,i) - com_v)
  
negative.code:   subroutine unbind_molecule(to_species)
      integer, intent(in) :: to_species
  
      integer :: i, p(3), cell_idx
      double precision :: x_new(3), dist, en1, en2
      logical :: too_close
  
      ! transfer mass
  