Complex Kohn variational principle for two-nucleon bound-state and scattering with the tensor potential

Complex Kohn variational principle is applied to the numerical solution of the fully off-shell Lippmann-Schwinger equation for nucleon-nucleon scattering for various partial waves including the coupled 3 S1-3 D1 channel. Analytic expressions are obtained for all the integrals in the method for a suitable choice of expansion functions. Calculations with the partial waves 1 S0, 1 P1, 1 D2, and 3 S1-3 D1 of the Reid soft core potential show that the method converges faster than other solution schemes not only for the phase shift but also for the off-shell t matrix elements. It is also shown that its is trivial to modify this variational principle in order to make it suitable for bound-stage calculations. The bound-state approach is illustrated for the 3 S1-3 D1 channel of the Reid soft-core potential for calculating the deuteron binding, wave function and the D state asymptotic parameters. (author)