  Elasticity property (i.e. no-particle creation) is used in the tree level
scattering of scalar particles in 1+1 dimensions to construct the affine Toda
field theory(ATFT) associated with root systems of groups $a_2^{(2)}$ and
$c_2^{(1)}$. A general prescription is given for constructing ATFT (associated
with rank two root systems) with two self conjugate scalar fields. It is
conjectured that the same method could be used to obtain the other ATFT
associated with higher rank root systems.
