中文摘要：

为了降低NaAlH4和LiAlH4的吸放氢温度，以及提高其吸放氢的动力学性能，采用基于密度泛函理论（DFT）的平面波赝势（PW-PP）方法，计算了HfCl4、ZrCl4掺杂在NaAlH4、LiAlH4中取代不同位置的Na（Li）、A1前后的电子结构及相关热力学性质。电子态密度及电荷布居等分析表明，Hf和Zr取代NaAlH4或LiAlH4中的Na或Li的几率要比Al的大，掺杂后Al-H键的作用部分减弱，导致Al-H键比较容易断裂，有利于Al-Zr、Al-Hf和H-H键的形成，从而降低反应温度。晶格振动的计算表明，（Na3Zr）Al4H16的Al-H键断裂对应的频率在1735-1825cm“的范围内，而（Na3Hf）A14H16的Al-H键断裂对应的频率在1500-1810cm-1的范围内，HfCl4掺杂在NaAlH4中的反应温度要比ZrCl4掺杂在NaAlH4中的反应温度要低一些，这和实验结果相吻合。

英文摘要：

In order to reduce the hydrogen absorption and desorption temperature of NaAIH4 and LiA1H4, and to improve the performance of hydrogen absorption and desorption kinetics, situations of HfC14 and ZrC14 defects in NaA1H4 and LiA1H4 were studied by using the plane-wave pseudo-po- tential （PW-PP） method based on the density functional theory （DFT）. The results of the electron density of states and charge population show that it is more possible for Hf and Zr to substitute Na or Li than A1 in NaA1H4 and LiA1H4. The strength of the AI--H bond was partially weakened so that the A1--H bond is broken relatively easily and the A1--Zr, A1--Hf, and H--H bonds can be formed more easily, implying the lower reaction temperature. The lattice vibration calculations show that the A1-H bond breakage in （Na3Zr） A14H16 and （N%Hf） Al4H16 is corresponding to a frequency within the range of 1 735 - 1 825 cm-l and 1 500 - 1 810 cm-1 , respectively. It is shown that Hf- Cl4 is superior to ZrCl4 in reducing the reaction temperature of NaAlH4, which is in good agreement with the experimental data.