N2分子在UO(100)表面的吸附与解离

Adsorption and Dissociation of N_2 Molecule on UO(100) Surface

运用密度泛函理论中广义梯度近似(GGA)的VWN-BP方法结合周期性平板模型,研究N2在UO(100)表面的吸附.研究表明,N2平行吸附在UO(100)表面穴位为最稳定吸附构型,吸附能为79.0kJ·mol-1.Mulliken布居分析显示,N2获得电子.吸附后,N—N伸缩振动频率发生红移,波数在1770-2143cm-1之间.态密度分析表明,U原子将d、f电子转移至N2的2π轨道.计算所得解离反应的能垒为266.9kJ·mol-1.

The adsorption of N2 molecule on the UO（100） surface was studied with periodic slab model by VWN-BP approach of GGA within the framework of density functional theory （DFT）. The results of geometry optimization indicated that the most stable structure of adsorption was N2 adsorbed parallelly on the hollow site with an adsorption energy of 79.0 kJ·mol-1. The analysis of Mulliken population and density of states indicated that 2π antibonding orbitals of N2 molecules got electrons from d and f orbitals in uranium. The vibration wave number of N—N range from 1770 to 2143 cm-1. Complete linear synchronous transit （LST） and quadratic synchronous transit （QST） were used to search the transition state for dissociation reaction. The predicted lowest energy barrier was 266.9 kJ·mol-1.