  A simple modification of the semiempirical model of Shevelko et al (J. Phys.
B: At. Mol. Opt. Phys. 38, 525 (2005)) is proposed for the calculation of
electron impact double ionization cross section of He^0, Li^(0,1+), B^(1+),
C^(1+,3+), O^(0-3+), Ar^(0-7+), Fe^(1+,3+-6+), Kr^(0-4+), Xe^(0-8+),
Pr^(1+-4+), Pb^(0-9+), Bi^(1+-3+,10+), and U^(0,10+,13+) atoms and positive
ions. The contributions from the direct double ionization of outer shell and
indirect processes of inner shells are also considered in the proposed
modification. Ionic correction and relativistic factor are also incorporated.
The results of the simplified model are compared with the experimental,
quantum, and other semiempirical calculations where available. It is found that
the proposed modification provides better performance than those obtained by
the existing semiempirical cross sections over the range of incident energies
and a significant number of atomic and ionic targets considered herein for the
description of experimental cross sections.
