  This paper compares the Wolf method to the shifted forces (SF) method for
efficient computer simulation of isotropic systems interacting via Coulomb
forces, taking results from the Ewald summation method as representing the true
behavior. We find that for the Hansen-McDonald molten salt model the SF
approximation overall reproduces the structural and dynamical properties as
accurately as does the Wolf method. It is shown that the optimal Wolf damping
parameter depends on the property in focus, and that neither the potential
energy nor the radial distribution function are useful measures for the
convergence of theWolf method to the Ewald summation method. The SF
approximation is also tested for the SPC/Fw model of liquid water at room
temperature, showing good agreement with both the Wolf and the particle mesh
Ewald methods; this confirms previous findings [Fennell & Gezelter, J. Chem.
Phys. {\bf 124}, 234104 (2006)]. Beside its conceptualsimplicity the SF
approximation implies a speed-up of a factor 2 to 3 compared to the Wolf method
(which is in turn much faster than the Ewald method).
