  We construct operators for simulating the scattering of two hadrons with spin
on the lattice. Three methods are shown to give the consistent operators for
PN, PV, VN and NN scattering, where P, V and N denote pseudoscalar, vector and
nucleon. Explicit expressions for operators are given for all irreducible
representations at lowest two relative momenta. Each hadron has a good helicity
in the first method. The hadrons are in a certain partial wave L with total
spin S in the second method. These enable the physics interpretations of the
operators obtained from the general projection method. The correct
transformation properties of the operators in all three methods are proven. The
total momentum of two hadrons is restricted to zero since parity is a good
quantum number in this case.
