Structures, simulated photoelectron spectroscopy, and electronic properties of CuASix(A = Sc, Cu, x ≤ 13) clusters: Relatively stable neutral pentagonal bipyramid structures of CuASi5

Structural design and optimization, simulated photoelectron spectroscopy, electronic properties and chemical bond analysis of CuASix(A = Sc, Cu, x ≤ 13) clusters were systematically studied using the PBE scheme to integrate with global search program of ABCluster. Firstly, neutral MS (the most stable structures) of CuASi5 of the basic 1 + 5 + 1 structures (1 metal + 5 silicons + 1 metal atoms) can be found as the basic units for assembling more lager clusters under the condition of neglecting distortions and minor changes. If the Cu atoms in Cu2Six(x ≤ 13) systems was replaced by one Sc atom, the geometries of MS will be reconstructed. Compared with the wheel geometries of Cu2Si12 and Cu2Si13, CuScSi12 and CuScSi13 clusters belong to near-wheel geometries with peripheral metal atoms. The neutral CuScSi5 and Cu2Si5 clusters possess relatively higher stability in all of cluster sizes. A combination of NPA analysis of CuASi5, sp of the Cu atom and spd of the Sc atom hybridizations were crucial to the chemical bonds of A-Si in the neutral CuASi5 clusters. In view of the higher SED value of the Cu2Si5 molecule, chemical bond analysis was carried out using MO, HLg and AdNDP analysis. 18 localized bonds and four delocalized bonds can play a positive role for the relative stabilities of neutral pentagonal bipyramid structures of Cu2Si5. Thus, the Cu2Si5 cluster with a lager HLg(1.80 eV) may be a good candidate for the basic unit of silicon-based semiconductor material assembly.

Pairwise Model Potential and DFT Study of Li+Nen Clusters (n = 1-20): The Structural, Electronic, and Thermodynamic Properties

The structural properties, relative stabilities, electronic, and thermodynamic properties, of Li+Nen (n = 1-20) clusters have been studied based on a pairwise model and density functional theory (DFT) methods. In the pairwise method, the potential energy surface considered interactions between Li+Ne, Ne - Ne, and many-body term. For the DFT calculations, the B3LYP functional combined with the 6-311 + + G (2d,2p) basis sets has been employed. In both methods, the Li+Ne6 cluster demonstrated high stability with an octahedral structure, where the Li+ cation was surrounded by Ne atoms. Thus, the octahedral Li+Ne6 structure was considered to be the core for larger cluster sizes. Relative stabilities were assessed based on binding energies, second-order differences of energies, transition dipole moment, and HOMO-LUMO energy gaps. Furthermore, thermodynamic properties were calculated, revealing that the formation process of Li+Nen clusters is endothermic and nonspontaneous.

COMPARATIVE INVESTIGATION OF THE EFFECT OF TYPE OF DENSITY FUNCTIONAL IN THE DETERMINATION OF GEOMETRICAL PARAMETERS IN A Cu COMPLEX

The effects of short-range electron correlation, long-range electron exchange, local and nonlocal parts of density, higher order gradients of density, and adding some percentage of Hartree–Fock exchange to the functional on the prediction of geometrical parameters were investigated. A copper complex namely 1,2-bis(1,4,7-triaza-1-cyclononyl) ethane copper (II) with Jahn–Teller distortion in octahedral geometry was used to evaluate the performance of 50 commonly available density functionals. The standard 3-21G basis set was used for all light elements, while pseudo potential LANL2DZ was used for the copper atom. The best bond lengths and bond angles were obtained using M05-2x and OP functionals respectively. Also in order to more accurate survey the performance of B3LYP, we used this functional with two all-electron basis sets (6-31G and 3-21G) and three basis sets involving effective core potentials (LANL2DZ/3-21G, LANL2DZ, and LACVP).

AB INITIO STUDY OF DIFFERENT PROBABLE STRUCTURES OF GROUP III ANTIMONIDES

Ab initio studies of the small ( AlSb , InSb , GaSb ) clusters is performed to investigate the changes in structural, vibrational and electronic properties. The calculated results clearly demonstrate that any change in the electronic configuration of the neutral clusters gives rise to noticeable changes in the structure. The structures of the neutral, positively and negatively charged clusters are fully optimized, taking the importance of the symmetry into account in all the cases. The changes in vibrational properties are explained keeping in mind the change in the interatomic distances due to any change in the electronic configuration.