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 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...

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 ...

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 ...

Using photoelectron spectroscopy and first principles molecular orbital calculations, we report the first observation of an abrupt change in the electronic structure of W4O m (m6 6) clusters at m 1⁄4 5 which is well below the bulk stoichiometric composition of tungsten oxide (WO3). The signature of this onset is established from an anomalous increase in the vertical detachment energies (VDE), a...

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...