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Abstract: First-principle calculations have been carried out to investigate the activation and adsorption of CO2 over Cu n clusters. The structural and electronic properties like optimized geometries, HOMO–LUMO energy levels, binding energy per atom (BE/n), adsorption energy (E ad), natural electronic configuration using NPA analysis and density of states (DOSs) of the pure Cu n and Cu n CO2 clusters in their ground state are thoroughly analyzed. Our results provide sound evidence for chemisorption and activation of CO2, on Cu n (n =7, 13, and 19) clusters with C–O bond stretched up to 1.20–1.30Å. The positive adsorption energy for CO2 adsorbed on the Cu n clusters suggests that the adsorption process is thermodynamically favorable. We find that the CO2 molecule, when adsorbed on one of the vertices of the icosahedral Cu13 cluster, has maximum adsorption energy (52.47kcalmol−1) and acts as a precursor to dissociate it into CO and atomic oxygen. The preferential adsorption sites for CO2 molecule have been identified. The interaction between Cu cluster and CO2 molecule that leads to the formation of the species has been understood in terms of charge transfer using NPA analysis. [Copyright &y& Elsevier]

Density functional calculations using B3LYP/6-311G method have been carried out for small to medium-sized lithium clusters (Li N, N = 2-30). The optimized geometries of neutral and singly charged clusters, their binding energies, ionization potential, electron affinity, chemical potential, softness, hardness, highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO) gap, and static dipole polarizability have been investigated systematically. In addition, we study the distribution of partial charges in detail using natural population analysis (NPA) in small-sized clusters (Li N, N = 2-10), both neutral and cationic, and demonstrate the correlation between symmetry and charge. Uniform distribution of charges in cationic clusters confirms them to be energetically more favorable than the neutral counterparts. Whenever possible, results have been compared with available data. An excellent agreement in every case supports new results as reliable predictions. A careful study of optimized geometries shows that Li9 is derivable from bulk Li structure, i.e., body centered cubic cell, and higher clusters have optimized shapes derived from this. Further, the turnover form two to three dimensional structure occurs at cluster size N = 6. The quantity α1/3 (α = polarizability) per atom is found to be broadly proportional to softness (per atom) as well as inverse ionization potential (per atom). The present work forms a sound basis for further study of large-sized clusters as well as other atomic clusters. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]