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標題
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Ab initio study of spin-forbidden unimolecular decomposition of carbon dioxide |
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學年
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88 |
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學期
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2 |
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出版（發表）日期
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2000/06/01 |
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作品名稱
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Ab initio study of spin-forbidden unimolecular decomposition of carbon dioxide |
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作品名稱（其他語言）
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著者
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黃德彥; Hwang, Der-yan; Mebel, Alexander A. M. |
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單位
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淡江大學化學學系 |
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出版者
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Elsevier |
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著錄名稱、卷期、頁數
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Chemical physics 256(2), pp.169-176 |
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摘要
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The results of ab initio G2(MP2), QCISD(T)/6-311+G(3df) and full valence active space CASSCF(16,12)/6-311+G(3df) calculations of the stationary points on the lowest singlet and triplet potential energy surfaces of carbon dioxide and their intersystem crossing show that spin-forbidden unimolecular decomposition of CO2 can proceed by two different mechanisms. The non-collinear channel goes through a C2v-symmetric minimum energy crossing point MSX1 in the vicinity of the bent local minimum 4 in the triplet state. Once on the triplet surface, the molecule has to overcome the barrier of 131.3 kcal/mol at transition state TS3 before yielding the products, Full-size image (<1 K). The collinear channel directly leads from CO21 to the products via linear MSX2. The barrier at MSX2, estimated as ∼135 kcal/mol, is higher than that for the non-collinear channel, but the probability of intersystem crossing for the collinear mechanism is expected to be higher than for the non-collinear channel, since the spin–orbit coupling value for MSX2 (Full-size image (<1 K)) is much higher than that for MSX1 (Full-size image (<1 K)). The two mechanisms of unimolecular decomposition of CO2 are expected to compete with each other and exhibit different mode-specific dynamics. Spin-forbidden fragmentation of CO2 is compared with the fragmentation of the isoelectronic N2O molecule. The mechanisms for the reverse Full-size image (<1 K) and Full-size image (<1 K) reactions are also discussed. |
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關鍵字
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語言
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英文 |
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ISSN
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0301-0104 |
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期刊性質
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國內 |
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收錄於
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產學合作
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通訊作者
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審稿制度
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否 |
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國別
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中華民國 |
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公開徵稿
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出版型式
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,電子版 |