
 Protein Dipole Moments Server 
  The quadrapole moments are now calculated according to the formula, for each atom i, Qx(i) = 0.5q(i)*(3x(i)**2  r(i)**2), and similar for Qy and Qz, where q(i) is the atom's partial charge, x(i) is its Xcoordinate and r(i) is its distance from the centerofmass origin. 
  In the pictures, the dipole vector is represented by a red line, and the truncated mass moment vector is a short line, half red and half fl. 
  The origin of the red dipole line corresponds with the net negative charge, and the far end with the net positive charge of the dipole moment. 
 bioportal.weizmann.ac.il /dipol (928 words) 
