We discuss the electrochemical reactions at the oxygen electrode of an aprotic Li-air battery. Using density functional theory to estimate the free energy of intermediates during the discharge and charge of the battery, we introduce a reaction free energy diagram and identify possible origins of the overpotential for both processes. We also address the question of electron conductivity through the Li2O2 electrode and show that in the presence of Li vacancies Li2O2 becomes a conductor.

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The structural, electronic and magnetic properties of Con clusters (n =2−20) have been investigated using density functional theory within the pseudopotential plane wave method. An unusual hexagonal growth pattern has been observed in the intermediate size range, n =15−20. The cobalt atoms are ferromagnetically ordered and the calculated magnetic moments are found to be higher than that of corresponding hcp bulk value, which are in good agreement with the recent SternGerlach experiments. The average coordination number is found to dominate over the average bond length to determine the effective hybridization and consequently the cluster magnetic moment.

We study the effect of doping on band gap in Mg-and Cd-doped zinc oxide nanostructures and molecular clusters. The fabrication of doped nanostructures was carried out via solution route. The lower doping efficiency of Cd than that of Mg has been explained in terms of binding energy. The band gap varied from 3.04 eV in Cd-doped ͑9.1 at. % of Cd͒ nanostructure to 3.99 eV in Mg-doped ͑16.8 at. % of Mg͒ nanostructure. Theoretical analysis using first-principles molecular dynamics techniques on pristine and doped ZnO clusters shows that the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital exhibits a similar variation as does the band gap in nanostructures with the varying concentration of Mg and Cd.

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K ͑M 1 ͒; and 1 alkali, alkaline earth or 3d / 4d transition metal atom ͑M 2 ͒ plus two to five ͑BH 4 ͒ − groups, i.e., M 1 M 2 ͑BH 4 ͒ 2-5 , using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M 1 ͑Al/ Mn/ Fe͒͑BH 4 ͒ 4 , ͑Li/ Na͒Zn͑BH 4 ͒ 3 , and ͑Na/ K͒͑Ni/ Co͒͑BH 4 ͒ 3 alloys are found to be the most promising, followed by selected M 1 ͑Nb/ Rh͒͑BH 4 ͒ 4 alloys.