The theory of dipole polarization as used in molecular mechanics energy functions is analyzed, and the difference in induction energy between an iterative (self-consistent) and non-iterative (one-step) scheme is derived. It is concluded that this difference is bound to be small in most cases, so that a non-iterative polarization model can be expected to give a satisfactory representation of the induction energy. This is demonstrated with examples of configurations of water molecules. The advantages of a one-step procedure are discussed. (C) 2004 Elsevier B.V. All rights reserved.