CAJ | 학술논문

采用基于密度泛函理论的第一性原理方法,通过计算MgH2两种不同表面((001)和(110))的几何、能态及电子结构,考察其表面稳定性、解氢热力学及其与微观原子及电子结构间的内在关系.结果显示:MgH2(001)和MgH2(110)表面均未发生结构重构现象,两者均为MgH2晶体的稳定解理面,相比而言,MgH2(110)表面具有更高的结构稳定性.平均解氢焓与单H原子解离焓的计算结果表明,MgH2(001)表面具有较佳的解氢热力学.原子及电子结构分析表明,MgH2表面的结构稳定性和解氢热力学与表面H、Mg原子各自的配位数以及体系在费米能级附近的能隙密切相关,即较少的配位数与较窄的能隙对应着表面较低的结构稳定性与较佳的解氢热力学性能.
채용기우밀도범함이론적제일성원리방법,통과계산MgH2량충불동표면((001)화(110))적궤하、능태급전자결구,고찰기표면은정성、해경열역학급기여미관원자급전자결구간적내재관계.결과현시:MgH2(001)화MgH2(110)표면균미발생결구중구현상,량자균위MgH2정체적은정해리면,상비이언,MgH2(110)표면구유경고적결구은정성.평균해경함여단H원자해리함적계산결과표명,MgH2(001)표면구유교가적해경열역학.원자급전자결구분석표명,MgH2표면적결구은정성화해경열역학여표면H、Mg원자각자적배위수이급체계재비미능급부근적능극밀절상관,즉교소적배위수여교착적능극대응착표면교저적결구은정성여교가적해경열역학성능.
@@@@Using first-principles method based on the density functional theory, the geometries, energetic and electronic structures of two different MgH2 (001) and (110) surfaces were calculated to investigate the surface stabilities, dehydrogenation thermodynamics and their intrinsic relations with the micro-atomic and micro-electronic structures. The results show that no apparent reconstruction occurs either for MgH2(001) surface or for MgH2(110) counterpart, which suggests that both of them are stable cleavage planes of MgH2 crystal. Comparatively, MgH2(110) surface exhibits a higher structural stability. The calculations of average desorption enthalpy and single H atom dissociation enthalpy show that MgH2(001) surface presents better dehydrogenation thermodynamics. The analysis of atomic and electronic structures implys that the structural stabilities and dehydrogenation thermodynamics of MgH2 surface are closely associated with the respective coordination number of H and Mg atoms located at surface layer as well as the energy gap near Fermi energy level of the system. Namely, the fewer coordination number and the narrower energy gap mean the lower structural stability and the better dehydrogenation thermodynamics of the surface.