Calculation of sequential hydrogen atom binding energies on a model lithium cluster

Density functional calculations have been performed to investigate the sequential hydrogen binding energies on a model Li18 cluster (Li18H2n+H2(Li18H2n+2, n=0-8). Data was generated for a sample of six different isomers for each Li18H2n system. The results seem to indicate that there is a slight increase in the incremental binding energy as the cluster becomes more hydrogenated. This has been attributed to the restructuring of the cluster geometry to form regions of a regular lattice as the number of bound H atoms increase. Natural population analyses indicate that the total charge transfer to each hydrogen atom is essentially constant at approximately 0.75 e. This value seems to be independent of the number of hydrogen atoms already on the cluster or the site of hydrogen atom binding. These results are consistent with previous analyses of charge transfer in lithium hydrides.