Several phosphorus-bearing molecules, such as the phosphine of interest here, have been detected in astrophysical media. With the aim of satisfying the precision required by the astrophysical community, we report the rate coefficients of PH₃ in collision with helium from low to moderate temperature. To this end, we constructed the first three-dimensional potential energy surface (3D-PES) of the PH₃–He van der Waals complex, which governs the nuclear motions. The 3D-PES was worked out by means of the standard coupled cluster with single, double and non-iterative triple excitation approach, in conjunction with the aug-cc-pVQZ basis set and complemented by mid-bond functions. This 3D-PES presents a well of 34.92 cm⁻¹ at {R, θ, Φ} = {5.76 a₀, 90°, 60°}. Afterwards, we incorporated this 3D-PES into time-independent close-coupling quantum dynamical computations to derive the inelastic cross-sections of rotational excitation of (ortho-) para-PH₃ after collision with He up to (1000) 500 cm⁻¹. Subsequently, we evaluated the rate coefficients for temperatures up to (100 K) 50 K populating the (41) 42 low-lying rotational levels of (ortho-) para-PH₃. These data were derived by averaging the cross-sections thermally over the Maxwell–Boltzmann velocity distribution. No general propensity rules are found. We also performed a comparison with the rates for NH₃–He. Differences are observed that invalidate the use of NH₃ rates for deducing accurate abundances of phosphine in cold astrophysical media. Our results should be of great help in determining accurate PH₃ abundances and, more generally, constraining the interstellar PH₃ chemistry better.

中文翻译：

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在低温至中温下与He碰撞的磷化氢的状态间非弹性速率系数

在天体物理介质中已检测到几种含磷分子，例如此处的目标膦。为了满足天体物理学界所要求的精度，我们报告了从低温到中温与氦气碰撞时PH ₃的速率系数。为此，我们构建了控制核运动的PH ₃ –He van der Waals络合物的第一个三维势能面（3D-PES）。3D-PES是通过具有单，双和非迭代三重激发方法的标准耦合簇，与aug-cc-pVQZ基础集结合并由中间键函数进行补充而制定的。该3D-PES呈现良好的34.92厘米^-1在{ - [R ， θ，Φ} = {5.76一个₀，90°，60°}。然后，我们将此3D-PES纳入与时间无关的紧密耦合量子动力学计算中，以推导与（He）碰撞直至（1000）500 cm ^-1后（邻）对位PH ₃的旋转激发的非弹性截面。。随后，我们评估了（邻位）对位PH ₃的（41）42低位旋转能级时高达（100 K）50 K的温度的速率系数。这些数据是通过对Maxwell-Boltzmann速度分布上的热横截面求平均而得出的。未找到一般倾向性规则。我们还与NH ₃的比率进行了比较-他。观察到的差异使使用NH ₃比率来推论冷天体物理介质中准确的磷化氢丰度无效。我们的结果对确定准确的PH ₃丰度应该有很大帮助，并且更广泛地讲，可以更好地约束星际PH _3的化学性质。