Positronium-hydrogen elastic scattering: The electronicS=1state

We have continued our investigation into the elastic scattering of positronium atoms by hydrogen atoms, extending the work to include the spin-one (triplet) state of the two electrons. Once again we have extracted the $S$-wave phase shifts from normalizable trial functions by examining the spatial behavior of the center-of-mass wave functions. An effective-range expansion linear in the positronium energy fits the results very well and leads to a scattering length $a^{\mathrm{}(-)\mathrm{}}\simeq 2.36a_0$, compared with the static result $a^{\mathrm{}(-)\mathrm{}}=2.476\mathrm{}{a}_0$ of Hara and Fraser. The $S$-wave total and ortho-para conversion cross sections are calculated by making use of both ${}_{}{}^1{}_{}{}^{}S$ and ${}_{}{}^3{}_{}{}^{}S$ results. In the ${}_{}{}^3{}_{}{}^{}S$ case, we see no indication of any resonances below the excitation threshold at 5.1 eV.