论文标题
H2的HC17O+的超细解析速率系数(j = 0)
Hyperfine resolved rate coefficients of HC17O+ with H2 (j = 0)
论文作者
论文摘要
甲基阳离子(HCO+)是分子云中最丰富的离子之一,在星际化学中起主要作用。因此,由于星际环境中最丰富的扰动物种,HCO+及其同位素的旋转激发及其同位素的准确碰撞速率系数至关重要,这对于非本地的热量平衡模型至关重要,值得特别注意。在这项工作中,我们确定了与H2碰撞(J = 0)时HC17O+的第一个超细解析速率系数。确实,尽管迄今为止尚未对其碰撞参数进行散射计算,但HC17O+同位素在天体物理建模应用中扮演着重要的作用。计算基于在CCSD(T)-F12A/AUG-CC-PVQZ理论水平上获得的新的四维(4D)势能表面。对相应的横截面值的测试指出,对于良好的近似,可以忽略H2旋转水平之间耦合的影响。因此,H2对撞机已被视为球形体,并且基于H2的五个方向的潜在平均值用于散射计算。针对HC17O+超精细结构解决的状态率系数已使用重新耦合技术计算为5至100 K的温度。这项研究提供了直接从完全量子关闭偶联方程式直接计算的HC17O+/H2非弹性速率系数的首次测定,从而支持了星际环境中HC17O+的未来辐射转移模量的可靠性。
The formyl cation (HCO+) is one of the most abundant ions in molecular clouds and plays a major role in the interstellar chemistry. For this reason, accurate collisional rate coefficients for the rotational excitation of HCO+ and its isotopes due to the most abundant perturbing species in interstellar environments are crucial for non-local thermal equilibrium models and deserve special attention. In this work, we determined the first hyperfine resolved rate coefficients of HC17O+ in collision with H2 (j=0). Indeed, despite no scattering calculations on its collisional parameters have been performed so far, the HC17O+ isotope assumes a prominent role for astrophysical modelling applications. Computations are based on a new four dimensional (4D) potential energy surface, obtained at the CCSD(T)-F12a/aug-cc-pVQZ level of theory. A test on the corresponding cross section values pointed out that, to a good approximation, the influence of the coupling between rotational levels of H2 can be ignored. For this reason, the H2 collider has been treated as a spherical body and an average of the potential based on five orientations of H2 has been employed for scattering calculations. State-to-state rate coefficients resolved for the HC17O+ hyperfine structure for temperature ranging from 5 to 100 K have been computed using recoupling techniques. This study provides the first determination of HC17O+/H2 inelastic rate coefficients directly computed from full quantum close-coupling equations, thus supporting the reliability of future radiative transfer modellings of HC17O+ in interstellar environments.