摘要
采用基于密度泛函理论(DFT)的第一原理及分子动力学(MD)方法,探讨了锂代氨硼烷LiNH2BH3(LAB)的稳定结构。基于此结构模拟得到的LAB的X射线衍射(XRD)图样与实验一致。通过计算LAB的晶格常数、键长及键角等结构参数发现:Li—N间的键长与LiNH2中的Li—N键长相当,而N—B间的键长却比氨硼烷(AB)中的N—B间键长要小,说明在LAB中N和B之间的共价交互作用比在AB中的强;LiNH2BH3从分子到晶体Li—N—B键角明显增大。电子结构分析显示,同AB相比,LAB中H的能级向费米能级处的移动、N与B交互作用的增强及能隙的减小导致了氢在氢化物中的稳定性降低,使其放氢性能较氨硼烷得到了一定程度的改善。
The stable struture of Lithium amidoborane LiNH2BH3（LAB） was investigated based on the density functional theory（DFT） and Moleculra Dynamics（MD） method.The X-ray Refraction Pattern（XRD） of the resulting LAB strcture was simulated and agreed with the experimental result.The decreased N—B bond length in LAB reveals a strong covalent interaction between N and B compared to that in ammonia-borane（AB）.The Li—N—B bond angle increases obviously from single molecule to crystalline phase LAB.Our calculated results show that the increased interaction between N and B,the movement of the hydrogen energy level towards the Fermi energy（EF） level,and the decreased energy gap in the LAB are responsible for the decreased stability of hydrogen in LAB.
出处
《沈阳师范大学学报（自然科学版）》
CAS
2011年第1期25-29,共5页
Journal of Shenyang Normal University:Natural Science Edition
基金
辽宁省自然科学基金项目(20102208)
沈阳师范大学博士启动基金项目(054-55440106014)
关键词
储氢材料
晶体结构
释氢性能
hydrogen storage material
crystal structure
hydrogen desorption property
