Structural Evolution of Carbon Dioxide under High Pressure
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- 作者：Cheng Lu ; Maosheng Miao ; Yanming Ma
- 刊名：Journal of the American Chemical Society
- 出版年：2013
- 出版时间：September 25, 2013
- 年：2013
- 卷：135
- 期：38
- 页码：14167-14171
- 全文大小：438K
- 年卷期：v.135,no.38(September 25, 2013)
- ISSN：1520-5126
文摘
Using an efficient structure search method based on a particle swarm optimization algorithm, we study the structural evolution of solid carbon dioxide (CO2) under high pressure. Our results show that, although it undertakes many structural transitions under pressure, CO2 is quite resistive to structures with C beyond 4-fold coordination. For the first time, we are able to identify two 6-fold structures of solid CO2 with Pbcn and Pa3̅ symmetries that become stable at pressures close to 1 TPa. Both structures consist of a network of C鈥揙 octahedra, showing hypervalence of the central C atoms. The C鈥揙 bond length varies from 1.30 to 1.34 脜 at the 4-fold to 6-fold transition, close to the C鈥揙 distance in the transition state of a corresponding SN2 reaction. It has been a longstanding and challenging objective to stabilize C in a hypervalent state, particularly when it is bonded with nonmetallic elements. Most of the work so far has focused on synthesizing organic molecules with a high coordination number of C. Our results provide a good measure of the resistivity of C toward forming hypervalent compounds with nonmetallic elements and of the barrier of reaction involving C鈥揙 bonds.