We propose a series of icosahedral matryoshka clusters of A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd), which possess large HOMO-LUMO gaps (1.29 to 1.54 eV) and low formation energies (0.06 to 0.21 eV/atom). A global minimum search using a genetic algorithm and density functional theory calculations confirms that such onion-like three-shell structures are the ground states for these A21B12 binary clu...

The FT-IR (4000-400 cm) and FTRaman (4000-100 cm) spectra of 2-chloro-4-nitroaniline (2Cl4NA) have been recorded using Bruker IFS 66 V spectrometer. An ab initio HF(HF/6-311G(d,p) and DFT(B3LYP/6-311G(d,p)) calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies,IR intensities and Raman activities. The study is extended to the HOMO LUMO analysis ...

Using an ab initio molecular-dynamics scheme ~the ‘‘fireball’’ scheme!, we determined the equilibrium structure of intermediate-size SinGem (n1m571) nanoclusters with and without hydrogen passivation on the surface. Due to the strong surface distortion, defect states are found to permeate the energy gap of SinGem clusters. However, the defect states are removed by adding H atoms on the surface ...

Phenyleneethynylene-based conjugated copolymers using benzo[1,2-d:4,5-d']bis[1,3]dioxole (BDO) in the repeating unit are reported. The electronic structure of the BDO unit imparts a localized HOMO topology while the LUMO is delocalized over the polymer backbone, so that the lowest optical absorption band of the polymer has considerable intramolecular charge transfer character. This contrasts wi...

C59-X (X= C, N, P, As and Sb) was studied by Density Functional Theory DFT at the B3LYP/3-21G** level. Group V elements have been selected to be substituted in the fullerene-C60 cage in order to show the effect of such substations upon structural and electronic properties of the studied molecules. It is found that elements of Group V doped C60 have an electronic structure similar to those of n-...

Structural, electronic and photovoltaic properties of pyrrole-furan copolymer incorporated with several electron-donating groups (EDGs) electron-withdrawing (EWGs) were investigated using density functional theory (DFT) time-dependent (TD-DFT). The intramolecular hydrogen bonding between the N…H site pyrrole O furan enhances a coplanar structure derivatives. substituted -NO2 shows significantly...

Heteroleptic (CN)2Ir(acac) (C ∧N = 4-CBppy (1); 5-CBppy (2), 4-fppy (4) CB = ortho-methylcarborane; ppy = 2-phenylpyridinato-C,N, 4-f ppy = 2-(4-fluorophenyl)pyridinato-C,N, acac = acetylacetonate) complexes were prepared and characterized. While 1 exhibits a phosphorescence band centered at 531 nm, which is red-shifted compared to that of unsubstituted (ppy)2Ir(acac) (3) (λem = 516 nm), the em...

We study Ge2O2 and Ge2O2 2 with density functional theory ~DFT! and photoelectron spectroscopy ~PES!. We find that Ge2O2 is a rhombus ~D2h), closed-shell molecule with a large HOMO-LUMO gap. The PES spectrum of Ge2O2 2 is obtained at four detachment photon energies: 1064, 532, 355, and 266 nm. Vibrational structure is resolved at the lowest photon energy with a single progression and a frequenc...

A dodecazinc silicotungstate K(20)Na(2)[Zn(6)(OH)(7)(H(2)O)(Si(2)W(18)O(66))](2)·34H(2)O (1) has been synthesized and characterized by X-ray crystallography, elemental analysis, infrared, UV-vis spectroscopy, cyclic voltammetry, acid-base titration, and DFT calculations. The twelve zinc atoms between the two [Si(2)W(18)O(66)](16-) frameworks make this complex more stable hydrolytically than the...

A detailed study of energy differences between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gaps) in protein systems and water clusters is presented. Recent work questioning the applicability of Kohn-Sham density-functional theory to proteins and large water clusters (Rudberg 2012 J. Phys.: Condens. Matter 24 072202) has demonstrated vanishing HOMO-LUMO gaps for thes...