Density Functional Theory Study On The Structures And Properties Of Lanthanum-Nickel Hydrogen Storage Alloy Clusters

In past decades,hydrogen storage alloy has attracted much attention because of its potential application as a new energy storage material.Especially,the La-Ni alloys as hydrogen storage materials have been studied extensively both theory and experiment. Until now,however,the research work in lanthanum-nickel clusters is very limited.In this work,the geometries and electronic properties of small La and Ni clusters were studied via density functional theory(B3LYP).The calculated results shown that: In La₂Ni_n(n=1-10)clusters,we found it was very especial for the six-numbered ring in La₂Ni₆ cluster,and the large numbers of these tings existed in hydrogen storage alloy. At the same time,we calculated the stability in various clusters,the result of the binding energy,the second differences of the total energy,the HOMO-LUMO gaps and the Mulliken charges showed that the La₂Ni₆ cluster was more stable than any others.Until now,it has not related report about La₂Ni₆ cluster;In La_mNi_nH_p(m=1-2,n=1-2,p=1-3) clusters,we analyzed the location of the hydrogen atoms,it showed that the H atoms tended to disperse at different edge combind with different La or Ni atoms,and the planes must contain one or more La atoms in our work,this special location of the hydrogen atoms were similar with the arrangement in crystal.At the same time,the spinning multiplicities of the lowest energy structures affected the geometry structure and the energy in small La_mNi_nH_p(m=1-2,n=1-2,p=1-3)clusters.From the growth mode of the small clusters,we found that the location of La-Ni system did not change too much,however,the H atoms changed.In addition,the analyze of the stability showed that in LaNiH_p(p=1-3)clusters,the LaNiH₃ cluster was more stable than any others,in La₂NiH_p(p=1-3)clusters,La₂NiH₂ cluster was more stable,in LaNi₂Hp(p=1-3)clusters, the analyze of binding energy and bond length showed the LaNi₂H₃ cluster was more stable,the ionization and HOMO-LUMO gaps showed the LaNi₂H clusters was more stable.