Abstract :
A new method of calculating exponential operators exp(−ßH), H being the Hamiltonian for the system, β being a complex number, is presented. The method is applicable for the two-body scattering or potential scattering H = H0 + V where the Hamiltonian H0 describes infinite translational motion of particles, and V is the interaction potential satisfying ordinary conditions of scattering theory. The method is tested by calculating the matrix elements 〈 exp(− ßH) r′〉 the isotropic exponential potential V = −V0 exp(−r/a).
