Evolution of the Properties of AlnNn Clusters with Size

Influence of the adsorption of toxic agents on the optical and electronic properties of B12N12 fullerene in the presence and absence of an external electric field

The interaction energies and optoelectronic properties of sarin (SF) and chlorosarin (SC) on the B₁₂N₁₂ with and without the presence of an electric field have been studied using density functional theory (DFT) calculations.

Carbon dioxide capture by planar (AlN)n clusters (n=3-5)

Searching for materials and technologies of efficient CO₂ capture is of the utmost importance to reduce the CO₂ impact on the environment. Therefore, the (AlN)_n clusters (n = 3-5) are researched using density functional theoretical calculations. The results of the optimization show that the most stable structures of (AlN)_n clusters all display planar configurations at B3LYP and G3B3 methods, which are consistent with the reported results. For these planar clusters, we further systematically studied their interactions with carbon dioxide molecules to understand their adsorption behavior at the B3LYP/6-311+G(d,p) level, including geometric optimization, binding energy, bond index, and electrostatic. We found that the planar structures of (AlN)_n (n = 3-5) can capture 3-5 CO₂ molecules. The result indicates that (AlN)_n (n = 3-5) clusters binding with CO₂ is an exothermic process (the capture of every CO₂ molecule on (AlN)_n clusters releases at least 30 kcal mol^-1 in relative free energy values). These analysis results are expected to further motivate the applications of clusters to be efficient CO₂ capture materials.

Analysis of the Structures and Properties of (GaSb)n (n = 4-9) Clusters through Density Functional Theory

An optimization strategy combining global semiempirical quantum mechanical search with all-electron density functional theory was adopted to determine the lowest energy structure of (GaSb)n clusters up to n = 9. The growth pattern of the clusters differed from those of previously reported group III-V binary clusters. A cagelike configuration was found for cluster sizes n ≤ 7. The structure of (GaSb)6 deviated from that of other III-V clusters. Competition existed between core-shell and hollow cage structures of (GaSb)7. Novel noncagelike structures were energetically preferred over the cages for the (GaSb)8 and (GaSb)9 clusters. Electronic properties, such as vertical ionization potential, adiabatic electron affinities, HOMO-LUMO gaps, and average on-site charges on Ga or Sb atoms, as well as binding energies, were computed.

Potential of AlN nanostructures as hydrogen storage materials

The capability of AlN nanostructures (nanocages, nanocones, nanotubes, and nanowires) to store hydrogen has been studied using gradient-corrected density functional theory. In contrast to bulk AlN, which has the wurtzite structure and four-fold coordination, the Al sites in AlN nanostructures are unsaturated and have two- and three-fold coordination. Each Al atom is capable of binding one H(2) molecule in quasi-molecular form, leading to 4.7 wt % hydrogen, irrespective of the topology of the nanostructures. With the exception of AlN nanotubes, energetics does not support the adsorption of additional hydrogen. The binding energies of hydrogen to these unsaturated metal sites lie in the range of 0.1-0.2 eV/H(2) and are ideal for applications under ambient thermodynamic conditions. Furthermore, these materials do not suffer from the clustering problem that often plagues metal-coated carbon nanostructures.

Theoretical study of structure and photoelectron spectroscopy of In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters

The geometries and vibrational frequencies of In(x)P(y)- and In(x)P(y) are investigated by hybrid B3LYP functional for x + y < or = 6 and CCSD(T) method for x + y < or = 3. As for the small clusters having two to three atoms, the geometrical and electronic structures and vibrational frequencies at the B3LYP level are in good agreement with those at the CCSD(T) level. Among the most stable structures of In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters the P-rich clusters are more stable than In-rich clusters. Moreover, we found that those P atoms in In(x)P(y)- and In(x)P(y) (x + y < or = 6) clusters prefer to form a P-P bond, triangle, quadrangle, and pentagon for y = 2, 3, 4, and 5, respectively. Also, the vertical detachment energies of In(x)P(y)- (x + y < or = 6) and electron affinities of In(x)P(y) (x + y < or = 6) clusters obtained by B3LYP are in good agreement with the experimental values available. Theoretically, we show that the electron affinity of In3P3 is very low because, as observed in the experiment, there is a formation of a new P-P bond after an electron is lost from In(3)P(3)-, and we find that the similar phenomena exhibit in In2P4(-) cluster as well.

First Principles Study of Neutral and Anionic (Medium-Size) Aluminum Nitride Clusters: AlnNn,n= 7−16

We report the results of a theoretical study of AlnNn (n=7-16) clusters that is based on density functional theory. We will focus on the evolution of structural and electronic properties with the cluster size in the stoichiometric AlN clusters considered. The results reveal that the structural and electronic properties tend to evolve toward their respective bulk limits. The rate of evolution is, however, slow due to the hollow globular shape exhibited by the clusters, which introduces large surface effects that dominate the properties studied. We will also discuss the changes induced upon addition of an extra electron to the respective neutral clusters.