  The system of three ${}^4\mathrm{He}$ atoms with realistic interactions is
studied in the momentum-space framework. It is demonstrated that short and
long-range difficulties encountered in the coordinate-space calculations can be
reliably resolved in the momentum-space calculations. Well-converged and
accurate results are obtained for the ground and excited trimer energies,
atom-dimer scattering length, phase shifts, inelasticity parameters, and
elastic and breakup cross sections. A significant correction to previously
published results is found for the elastic cross section at very low energy.
