  In this work, we derive a correct expression for the one--component plasma
(OCP) energy via the angular--averaged Ewald potential (AAEP). Unlike E.~Yakub
and C.~Ronchi (J. Low Temp. Phys. 139, 633 (2005)), who had tried to obtain the
same energy expression from a two--component plasma model, we used the original
Ewald potential for an OCP. A constant in the AAEP was determined using the
cluster expansion in the limit of weak coupling. The potential has a simple
form suitable for effective numerical simulations. To demonstrate the
advantages of the AAEP, we performed a number of Monte--Carlo simulations for
an OCP with up to a million particles in a wide range of the coupling
parameter. Our computations turned out at least two orders of magnitude more
effective than those with a traditional Ewald potential. A unified approach is
offered for the determination of the thermodynamic limit in the whole
investigated range. Our results are in good agreement with both theoretical
data for a weakly coupled OCP and previous numerical simulations. We hope that
the AAEP will be useful in path integral Monte Carlo simulations of the uniform
electron gas.
