CCL: Visualization of quadrupole moments

 Sent to CCL by: "Anselm HC Horn"
 [anselm.horn_._chemie.uni-erlangen.de]
 Dear all,
 I wonder whether there is a way to easily visualize arbitrary quadrupole
 moments.
 For dipoles (x,y,z component) a simple arrow (vector) is sufficient, as used in
 many visualization programs. However, quadrupole moments consist of a traceless
 symmetrical 3x3 matrix, so there are six different values (Qxx, Qyy, Qzz, Qxy,
 Qxz, Qyz).
 In textbooks quadrupole moments of planar molecules are often represented by a
 set of four charges around a center. So, a possible solution could be to extend
 this set of charges; but this results in a cloud of charges (the size of which
 could be represented by different sphere radii), that seems unsuited for
 visualization.
 Any hints and ideas are welcome!
 Best regards,
 Anselm Horn
 Computer Chemie Centrum
 Friedrich-Alexander-Universiaet Erlangen-Nuernberg