【摘要】 采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,计算了LiAlH4分解反应中各个产物的晶胞参数、电子结构、生成焓和分解反应的反应焓.反应中各固态、气态物质的晶胞的结构优化后的晶格参数与相应的实验值均符合得较好.对LiAlH4与Li3AlH6的电子结构分析均表明,其中的Al—H键为共价键、Li—H键为离子键.对各分解反应的反应焓计算结果表明,(1)LiAlH4→1/3Li3AlH6+2/3Al+H2,(2)1/3Li3AlH6→LiH+1/3Al+1/2H2及(3)LiH+Al→LiAl+1/2H2均为吸热反应,298K时计算的反应焓分别为14.3、14.9与50.9kJ·mol-1,与相应的实验值符合得较好.更多还原

【Abstract】 The electronic structures, formation enthalpies, and reaction enthalpies of Li-Al-H system complex were investigated using plane-wave pseudo-potential method based on density functional theory. Calculated cell parameters were in agreement with experiment. The interaction between Al and H atoms was strong covalent bond and the interaction between Li and H atoms was strong ionic bond in both LiAlH4 and Li3AlH6. The calculated reaction enthalpies for reactions (1) LiAlH4→1/3Li3AlH6+2/3Al+H2, (2) 1/3Li3AlH6→LiH+1/3Al+1/2H2, and (3) LiH+Al→LiAl+1/2H2 were 14.3, 14.9, and 50.9 kJ·mol-1 at 298 K, respectively, which were in agreement with experiment results.更多还原