Abstract For any simple connected graph G of order n , having eigen spectrum μ 1 ≥ 2 ⋯ with middle eigenvalues H and L where = ⌊( + 1)/2⌋ ⌈( 1)/2⌉, the HOMO–LUMO gap is defined as Δ . In this article, a upper bound for corresponding to special class bipartite graphs estimated. As an application, bounds certain classes nanotubes nanotori are

Clusters play important role for understanding and transferring microscopic to macroscopic properties.Geometric and electron properties of Small nickel clusters up to the tetramer has been investigated by Density Functional Theory (DFT). Raising the number of nickel clusters atoms were indicated decreasing the average equilibrium (Ni-Ni) distance of atoms and also the binding energy of per atom...

Theoretical studies have been carried out to investigate the unusual reactivity of Ag15 + cations with oxygen. Our previous work has shown that the reactivity of free metal clusters with oxygen entails a spin excitation that causes reduced reactivity in clusters with filled electronic shells and large HOMO-LUMO gaps. Earlier experiments on Ag15 + have shown that the cluster exhibits remarkable ...

This paper discusses the fundamental features of the dielectric-dependent screened exchange potential approach for organic molecules and photocell materials. The energy difference (gap) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is a key factor when designing organic photocell materials. The magnitude of this energy gap strongly depe...

In this paper theoretical study by using DFT method on three conjugated compound based on 2-styryl-5-phenylazo-pyrrole is reported. These dyes contain one carboxy, two carboxy and one sulfonic acid anchoring groups, the aim is to investigate their effects on the electronic structure. The theoretical knowledge of the HOMO and LUMO energy levels of the components is cannot be ignored in investiga...

AIDS is a pandemic responsible for more than 35 million deaths. The emergence of resistant mutations due to drug use is the biggest cause of treatment failure. Marine organisms are sources of different molecules, some of which offer promising HIV-1 reverse transcriptase (RT) inhibitory activity, such as the diterpenes dolabelladienotriol (THD, IC50 = 16.5 µM), (6R)-6-hydroxydichotoma-3,14-diene...

The insertion of phenyl acetylenes at the reactive positions indeno[1,2- b ]fluorene leads to tune its optoelectronic and magnetic properties. Furthermore, single-molecule conductance has been investigated for first time.

Our recently proposed theoretical formulation based on Bethe–Salpeter G(0)W(0) methodology is applied here to explore the quasiparticle and optical spectra of anthracene (C(14)H10) placed close to a metallic surface. Special attention is paid to explore how the energy shift and decay width of the low-lying anthracene bright excitons p, α and β depend on the type of the adjacent surface (describ...

Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties of Ag-doped gold clusters have been calculated using density functional theory. The ...

the research in the short-chain organic -conjugated molecules has become one of the most interesting topics in the fields of chemistry. these compounds have become the most promising materials for the optoelectronic device technology. the use of low band gap materials is a viable method for better harvesting of the solar spectrum and increasing its efficiency. the control of the band gap of th...