A computational code based on an elaborate coupled static approach is developed for the treatment of the elastic and inelastic scattering of positrons by positroniums. The inelastic channel is chosen as a mixture of 2s− and 2p-states. The 2×2 reactance matrices as well as the corresponding partial cross sections corresponding to 0 ≤ℓ≤ 6 are determined for the first time at wide range of total energies below the second excitation threshold of the positronium, i.e. below 6.044 eV. The effect of adding the polarization potential to the first channel is explored. Partial and total cross sections are also calculated at high energies (between 10 and 500 eV) in order to compare present results of positronium formation with those obtained by other authors for inelastic collisions of positron with hydrogen atoms.
