Studying on geometrical structure and vibrational spectrum of polymerization aluminohydride (AIH₃)_n (n=1∼3)

The possible geometrical structure of polymerization Aluminohydride (AIH₃)_n (n=1∼3) have been optimized computation, based on different methods of B3P86, B3LYP, B3PW91 and 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 (E_T), binding energy (E_BT), average binding energy (E_αν), ionization potential (E_IP), energy crack (E_g), Fermi level (E_F) and so on. The results indicated the ground state of Aluminohydride all are 1 heavy condition and the electronic state are ¹A. The most stable geometry configuration of AIH₃ molecule is the planar triangle withD_3h, Al₂H₆ is the symmetrical ethylene type with D_2h spatial structure, and between H-Al produces the hydrogen bridge type with three center double electronic key, Al₃H₉ is the D_3h 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 Al₃H₉ is the most stable molecule in (AlH₃)_n (n=1∼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. (authors)