  We consider random walk model of a semi-flexible polymer chain on a square
and a cubic lattice to enumerate conformations of the polymer chain in two and
three dimensions, respectively. The bending energy of the chain is assumed as
the key factor which controls the minimum average length of the chain in
between two successive bends in the chain; and the average length of the chains
per unit bend is defined as the persistence length of the polymer chain. It has
been found that the minimum energy required to bend the chain is expressed in
the form of simple relation which includes space dimensionality, step fugacity
and persistence length.
