  Bending of DNA from a straight rod to a circular form in presence of any of
the mono-, di-, tri- or tetravalent counterions has been simulated in strong
Coulomb coupling environment employing a previously developed energy
minimization simulation technique. The inherent characteristics of the
simulation technique allow monitoring the required electrostatic contribution
to the bending. The curvature of the bending has been found to play crucial
roles in facilitating electrostatic attractive potential energy. The total
electrostatic potential energy has been found to decrease with bending which
indicates that bending a straight DNA to a circular form or to a toroidal form
in presence of neutralizing counterions is energetically favorable and
practically is a spontaneous phenomenon.
