Inelastic cross sections and rate coefficients for collisions between CO and H2

Q2 Physics and Astronomy

Molecular Astrophysics Pub Date : 2017-03-01 DOI:10.1016/j.molap.2017.01.003

Christina Castro , Kyle Doan , Michael Klemka , Robert C. Forrey , Benhui Yang , Phillip C. Stancil , N. Balakrishnan

{"title":"Inelastic cross sections and rate coefficients for collisions between CO and H2","authors":"Christina Castro , Kyle Doan , Michael Klemka , Robert C. Forrey , Benhui Yang , Phillip C. Stancil , N. Balakrishnan","doi":"10.1016/j.molap.2017.01.003","DOIUrl":null,"url":null,"abstract":"<div>A five-dimensional coupled states (5D-CS) approximation is used to compute cross sections and rate coefficients for CO+H2 collisions. The 5D-CS calculations are benchmarked against accurate six-dimensional close-coupling (6D-CC) calculations for transitions between low-lying rovibrational states. Good agreement between the two formulations is found for collision energies greater than 10cm−1. The 5D-CS approximation is then used to compute two separate databases which include highly excited states of CO that are beyond the practical limitations of the 6D-CC method. The first database assumes an internally frozen H2 molecule and allows rovibrational transitions for v ≤ 5 and j ≤ 30, where v and j are the vibrational and rotational quantum numbers of the initial state of the CO molecule. The second database allows H2 rotational transitions for initial CO states with v ≤ 5 and j ≤ 10. The two databases are in good agreement with each other for transitions that are common to both basis sets. Together they provide data for astrophysical models which were previously unavailable.</div>","PeriodicalId":44164,"journal":{"name":"Molecular Astrophysics","volume":"6 ","pages":"Pages 47-58"},"PeriodicalIF":0.0000,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molap.2017.01.003","citationCount":"6","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Molecular Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2405675816300446","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Physics and Astronomy","Score":null,"Total":0}

引用次数: 6

Abstract

A five-dimensional coupled states (5D-CS) approximation is used to compute cross sections and rate coefficients for CO+H₂ collisions. The 5D-CS calculations are benchmarked against accurate six-dimensional close-coupling (6D-CC) calculations for transitions between low-lying rovibrational states. Good agreement between the two formulations is found for collision energies greater than 10 cm⁻¹. The 5D-CS approximation is then used to compute two separate databases which include highly excited states of CO that are beyond the practical limitations of the 6D-CC method. The first database assumes an internally frozen H₂ molecule and allows rovibrational transitions for v ≤ 5 and j ≤ 30, where v and j are the vibrational and rotational quantum numbers of the initial state of the CO molecule. The second database allows H₂ rotational transitions for initial CO states with v ≤ 5 and j ≤ 10. The two databases are in good agreement with each other for transitions that are common to both basis sets. Together they provide data for astrophysical models which were previously unavailable.

查看原文本刊更多论文

CO和H2碰撞的非弹性截面和速率系数

采用五维耦合态(5D-CS)近似计算了CO+H2碰撞的截面和速率系数。5D-CS计算以精确的六维紧密耦合(6D-CC)计算为基准，用于低洼旋转振动状态之间的转换。当碰撞能量大于10 cm−1时，两种公式之间的一致性很好。然后使用5D-CS近似计算两个独立的数据库，其中包括超出6D-CC方法实际限制的CO的高激发态。第一个数据库假设一个内部冻结的H2分子，并允许v≤5和j≤30的旋转振动跃迁，其中v和j是CO分子初始状态的振动和旋转量子数。第二个数据库允许H2旋转跃迁的初始CO状态，v≤5和j≤10。对于两个基集共有的转换，这两个数据库彼此非常一致。它们一起为天体物理模型提供了以前无法获得的数据。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Molecular Astrophysics ASTRONOMY & ASTROPHYSICS-

自引率

0.00%

发文量

期刊介绍： Molecular Astrophysics is a peer-reviewed journal containing full research articles, selected review articles, and thematic issues. Molecular Astrophysics is a new journal where researchers working in planetary and exoplanetary science, astrochemistry, astrobiology, spectroscopy, physical chemistry and chemical physics can meet and exchange their ideas. Understanding the origin and evolution of interstellar and circumstellar molecules is key to understanding the Universe around us and our place in it and has become a fundamental goal of modern astrophysics. Molecular Astrophysics aims to provide a platform for scientists studying the chemical processes that form and dissociate molecules, and control chemical abundances in the universe, particularly in Solar System objects including planets, moons, and comets, in the atmospheres of exoplanets, as well as in regions of star and planet formation in the interstellar medium of galaxies. Observational studies of the molecular universe are driven by a range of new space missions and large-scale scale observatories opening up. With the Spitzer Space Telescope, the Herschel Space Observatory, the Atacama Large Millimeter/submillimeter Array (ALMA), NASA''s Kepler mission, the Rosetta mission, and more major future facilities such as NASA''s James Webb Space Telescope and various missions to Mars, the journal taps into the expected new insights and the need to bring the various communities together on one platform. The journal aims to cover observational, laboratory as well as computational results in the galactic, extragalactic and intergalactic areas of our universe.