Stability and structure of Li_nH molecules (n=3-6):experimental and density functional study

摘要

The molecules Li_3H and Li_4H have been identified in mass-spectrometric measurements over solutions of hydrogen in liquid Li,and the gaseous equilibria of the reactions:Li_3H+Li=Li_2H+Li_2,Li_3H+Li_2=Li_2H+Li_3,Li_3H+Li=LiH+Li_3,Li_3H+LiH=2Li_2H,and Li_4H+Li_2=Li_3H+Li_3 have been measured.Density functional calculations of Li_nH molecules (n=3-6) provide structures,vibrational frequencies,ionization energies,and free energy functions of these molecules,and these are used to estimate the enthalpies of these reactions and the atomization energies of Li_3H (119.4 kcal/mol) and Li_4H(151.8 kcal/mol).