in the present work, the structural and electronic properties, and conductivity of (5,5) and (6,6) single walled carbon nanotubes in the ground state have done by using the hartree-fock and density functional theory dft-b3lyp/6-31g* level. delocalization of charge density between the bonding or lone pair and antibonding orbitals calculated by nbo (natural bond orbital) analysis. these methods a...

The influence of the insertion/addition of a benzene ring to the natural nucleic acid bases on the local aromaticity of the so-called size-expanded (xN, with N being adenine, guanine, cytosine, and thymine) bases is examined. To this end, the local aromaticity of the six- and five-membered rings in both the natural bases and their benzoderivatives is determined using HOMA, NICS, aromatic fluctu...

The electronic structure of two series of small titanium oxide clusters, TiOy (y51 – 3) and (TiO2)n (n51 – 4), is studied using anion photoelectron spectroscopy. Vibrationally resolved spectra are obtained for TiO and TiO2 . Six low-lying electronic states for TiO are observed with five of these excited states resulting from multielectron transitions in the photodetachment processes. TiO2 is fo...

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...

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 ...

Vanadium oxide clusters, (V2O5)n, have been predicted to possess interesting polyhedral cage structures, which may serve as ideal molecular models for oxide surfaces and catalysts. Here we examine the electronic properties of these oxide clusters via anion photoelectron spectroscopy for (V2O5)n(-) (n = 2-4), as well as for the 4d/5d species, Nb4O10(-) and Ta4O10(-). Well-resolved photoelectron ...

In the present work, the structural and electronic properties, and conductivity of (5,5) and (6,6) Single Walled Carbon Nanotubes in the ground state have done by using the Hartree-Fock and density functional theory DFT-B3LYP/6-31G* level. Delocalization of charge density between the bonding or lone pair and antibonding orbitals calculated by NBO (natural bond orbital) analysis. These methods a...

The geometric and electronic structures of all-trans polyacetylene (PA) molecule in neutral, cationic, and anionic states have been studied theoretically by density functional theory method at the B3LYP/6-31+G* level. The results show that both the geometric and electronic structures of the PA molecule are sensitive to the external electric field (EF). For neutral PA molecule, with the increase...

We propose a third-order time-dependent perturbation theory approach to describe the chemical surfaceenhanced Raman spectroscopy of molecules interacting with two-dimensional (2D) surfaces such as an ideal 2D metal and graphene, which are both 2D metallic monolayers. A detailed analysis is performed for all the possible scattering processes involving both electrons and holes and considering the...