Abstract

Collisions of the metastable antiprotonic helium atoms with the atoms of the medium cause, among other processes, transitions between hyperfine structure (HFS) states, as well as shifts and broadening of microwave M1 spectral lines. To obtain the interaction potential matrix (\(\bar{p}\) \(\bar{He}^{+}){-}\textrm{He}\), the potential energy surface (PES) is calculated by the unrestricted Hartree–Fock method with consideration of the electron correlations within the second-order of perturbation theory (MP2). With this potential, the system of equations of close coupling of the HFS channels is numerically solved; the cross sections and transition rates, shifts, and broadenings of M1 spectral lines are calculated; they are then used to solve the kinetic equation that determines the time evolution of the HFS state density matrix. The results of these calculations are compared with the experimental data and with the results of model calculations.

中文翻译：

---

反质子的超精细结构$$ {} ^ {\ mathbf {4}} $$ He在与介质原子碰撞中的跃迁：相互作用从头算

摘要

在其他过程中，亚稳态反质子氦原子与介质原子的碰撞会导致超精细结构（HFS）状态之间的过渡，以及微波M1谱线的偏移和展宽。获取交互电位矩阵（\（\ bar {p} \） \（\ bar {He} ^ {+}）{-} \ textrm {He} \），势能面（PES）是通过无限制Hartree-Fock方法计算的，其中考虑了二阶扰动理论（MP2）中的电子相关性。有了这个潜力，就可以对HFS通道的紧密耦合方程组进行数值求解。计算出M1谱线的横截面和跃迁速率，位移和展宽；然后将它们用于求解确定HFS状态密度矩阵随时间变化的动力学方程。将这些计算的结果与实验数据以及模型计算的结果进行比较。