Positron scattering on atomic and molecular targets is a two-centre problem due to the possibility of rearrangement (Ps-formation) processes. In certain kinematic regions, single-centre expansion methods can be applied to two-centre scattering problems. In such approaches, however, information about Ps-formation and direct ionization processes are combined into excitation amplitudes of positive-energy pseudostates. In this report we show that Ps-formation amplitudes can be extracted using the total scattering wave function, which we reconstruct from single-centre convergent close-coupling calculations. The method is applied to positron scattering from hydrogen and lithium atomic targets. Excellent agreement with the two-centre theoretical benchmark results show the validity of the proposed technique.

由于重排（Ps 形成）过程的可能性，原子和分子目标上的正电子散射是一个双中心问题。在某些运动学区域，单中心扩展方法可以应用于双中心散射问题。然而，在这种方法中，关于 Ps 形成和直接电离过程的信息被组合成正能量赝态的激发振幅。在本报告中，我们展示了可以使用总散射波函数提取 Ps 形成幅度，我们从单中心会聚紧密耦合计算重建。该方法应用于氢和锂原子靶的正电子散射。与两个中心理论基准结果的极好一致性表明了所提出技术的有效性。