anchor.diff:    do_lennard_jones = PTread_l(config, 'do_lennard_jones', loc=params_group)
     rattle_pos_tolerance = PTread_d(config, 'rattle_pos_tolerance', loc=params_group)
     rattle_vel_tolerance = PTread_d(config, 'rattle_vel_tolerance', loc=params_group)
  +
  +  do_quaternion  = PTread_l(config, 'do_quaternion', loc=params_group)
  +  quaternion_treshold = PTread_d(config, 'quaternion_treshold', loc=params_group)
   
     do_elastic = PTread_l(config, 'do_elastic', loc=params_group)
     if (do_elastic) elastic_k = PTread_d(config, 'elastic_k', loc=params_group)
  
positive.code:   type(polar_fields_t) :: polar
    integer(HID_T) :: polar_id
  
    logical :: do_rattle, do_read_links, do_lennard_jones, do_elastic
    integer, allocatable :: links(:,:)
    double precision, allocatable :: links_d(:)
    double precision :: link_treshold
  
negative.code:   double precision :: unit_r(3)
    double precision :: com_pos(3), head_pos(3)
    integer :: head
    type(rigid_body_t) :: rigid_janus
    double precision :: quaternion_treshold
  
    integer, parameter :: block_length = 8
    type(axial_correlator_t) :: axial_cf
  