聚合型铝氢化物(AlH3)n(n=1～3)的几何结构与振动光谱的研究

摘要

采用不同方法B3P86、B3LYP、B3PW91和MP2,结合Dunning的相关一致基组cc-PVTZ,对聚合型铝氢化物(AlH3)n(n=1～3)分子的可能几何构型进行优化计算,通过比较计算结果,发现密度泛函DFT中的方法B3P86计算的能量最低.本文采用B3P86方法得出最稳定构型的几何参数、电子结构、振动频率等性质参数,并给出最稳定结构的总能量(Er)、结合能(EBT)、平均结合能(E∞)、电离势(EIP)、能隙(Eg)、费米能级(EF)和差分吸附氢原子能(Ediff).结果表明:三种铝氢化物分子基态都为1重态,电子态都为1A；AlH3分子的最稳定几何构型为D3h的平面三角形结构；Al2 H6为对称性乙烯式D2h立体结构,HAl之间生成氢桥式三中心双电子键;Al3 H9为D3h立体结构,也生成氢桥式三中心双电子键,但三个氢桥三中心双电子键彼此隔离.最后分析了三种氢化物的红外和拉曼光谱、平均结合能、电离势、能隙和费米能级等特性,说明(AlH3)n(n=1～3)三分子中Al3H9最稳定,H-Al桥键键长比端键更长,红外光谱强度最大,差分吸附氢原子能最大,具有较强的储氢性能.%The possible geometrical structure of polymerization Aluminohydride(AlH3),(n=l-3) have been optimized computation, based on different methods of B3P86,B3LYP.,B3PW91and MP2 with the Dunning related consistent base group cc-PVTZ. Comparing the computational results, it can find the total energies are lowest with B3P86 method. The configuration geometric parameter, electronic structure, vibrational frequency and spectrum of the most stable structure were obtained using the above method B3P86, and given total energy (ET), binding energy (EBT),average binding energy (Eav), ioni-zation potential (EIP), energy crack (Eg), Fermi level (EF) and so on. The results indicated the ground state of Aluminohydride all are 1 heavy condition and the electronic state are1 A. The most stable geometry configuration of A1H3 molecule is the planar triangle withD3h, Al2 H6 is the symmetrical ethylene type with D2h spatial structure, and between H -Al produces the hydrogen bridge type with three center double electronic key, A13H9 is the D3h spatial structure, also production hydrogen bridge type with three center double electronic key, but three hydrogen bridge type each other isolation. The ultimate analysis of the Infrared and Raman spectrum, the average binding energy, the ionization potential, the energy gap and Fermi level and so on characteristic. It explained that Al3 H9 is the most stable molecule in (AlH3),(n=l~3), the H-Al bridge bond key long is longer than the terminal linkage, the infrared intensity of strongest peak is maximal value and the differential adsorption energy per hydrogen is strongest, it has the best adsorption on H atom.