CO_2水合物气体分子笼占据状态的第一性原理研究

First-Principles Study on Cage Occupancy of CO_2 Hydrate

以CO2水合物形式储存是值得研究的一种方法,其中,用CO2置换海底天然气水合物中的CH4,达到开采天然气水合物中CH4的目的,同时将CO2作为水合物永久储存于海底,可起到经济和环保双重作用.由于CO2水合物在工程应用以及科学研究中有着重要的价值,尽管人们对CO2水合物已有不少了解,但仍然诸多问题(例如小笼占据状态尚存在争议),有待进行深入的研究.利用第一性原理的密度泛函理论,对CO2水合物气体分子不同笼占据状态的能量进行计算,结果表明以CO2气体分子仅占据大笼的情形能量最低,从而证明了CO2气体分子仅占据大笼的情形是最有可能存在,与实验结果吻合,所得结论有参考价值.

The energies of different cage occupancy states of CO2 hydrate molecules have been studied by using the first-principles with the density functional theory.The result indicates that the energy of this state is the lowest when CO2 gaseous molecules only occupy big cages.This suggests that only large cage occupancy is the most possible state,which is in agreement with the experimental observation.The obtained conclusion has some reference meaning.