CDS&E: Mixed Quantum/Classical Theory for the Collisional Quenching of Interstellar Complex Organic Molecules

马奎特大学的Dmitri Babikov得到了化学系化学理论、模型和计算方法项目的一个奖项的支持，该项目预测了几种对天体化学应用很重要的分子的碰撞淬灭率。这些数据是在相关的广泛温度范围内获得的，将通过在BASECOL数据库中公布这些数据的方式提供给广大科学界，特别是天文学家。这些信息被纳入天体物理学界目前使用的辐射转移代码中，将使天文学家能够量化这些分子在星前核心和原恒星喷流中的丰度。旋转非弹性碰撞的标准量子计算在更高的碰撞能量和更重的分子（如星际复杂有机分子（iCOM））中变得非常苛刻。为了克服这一障碍，建议开发一种实用的计算处理散射的碰撞伙伴的相对运动是经典描述，而他们的内部自由度（旋转，振动）仍然描述量子力学。这种方法预计将是准确的和计算负担得起的。为了成功地定量解释天体物理观测，必须知道典型背景气体（如He和H2）在宽温度范围内对发光分子的碰撞状态-状态激发/猝灭的横截面。然而，这些信息在很大程度上是不可用的，也没有简单的方法从实验中获得。Dmitri Babikov正在开发一种混合量子/经典理论（MQCT）和一套用户友好的程序，用于有效模拟非弹性分子碰撞，捕获散射相位对微分截面，散射到内部共振能量转移的重要影响，并揭示PES各向异性的作用。在这个项目中，将对几个SOLIS分子进行非弹性散射的MQCT计算（太空中的生命种子：包括甲醇（CH 3OH）、甲酸甲酯（HCOOCH 3）、二甲醚（CH 3 OCH 3）、乙醛（CH 3 COH）和甲酰胺（H2 NCOH），在类太阳原恒星中通常存在的温度范围内与He和H2碰撞，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dmitri Babikov of Marquette University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to predict the collisional quenching rates of several molecules important for astrochemical applications. These data, obtained for the relevant broad range of temperatures, will be delivered to the scientific community at large, and especially to astronomers, by means of publishing these data in the database BASECOL. Being incorporated into the radiation transfer codes presently in use in the astrophysics community, this information will enable astronomers to quantify the abundance of these molecules in pre-stellar cores and proto-stellar jets. The standard quantum calculations of rotationally inelastic collisions become prohibitively demanding at higher collision energies and for heavier molecules, such as the interstellar complex organic molecules (iCOMs). To overcome this obstacle, it is proposed to develop a practical computational treatment of scattering where the relative motion of collision partners is described classically, while their internal degrees of freedom (rotation, vibration) are still described quantum mechanically. This approach is expected to be both accurate and computationally affordable. For the successful quantitative interpretation of astrophysical observations it is imperative to know cross sections for collisional state-to-state excitation/quenching of the light-emitting molecules by typical background gasses, such as He and H2, across a broad range of temperatures. This information, however, is largely unavailable and there is no simple way of obtaining this from experiments. Dmitri Babikov is developing a mixed quantum/classical theory (MQCT) and a user-friendly suite of programs for efficient simulations of inelastic molecular collisions, capturing the effects of scattering phase important for differential cross-sections, translational-to-internal resonant energy transfer and revealing the role of PES anisotropy. In this project MQCT calculations of inelastic scattering will be carried out for several SOLIS molecules (seeds of life in space: includes methanol (CH3OH), methyl formate (HCOOCH3(, dimethyl ether (CH3OCH3(, acetaldehyde (CH3COH) and formamide (H2NCOH), colliding with He and H2 in temperature ranges that are typically found in solar-like proto-stars, and in interstellar and circumstellar environments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.