Electronic structure, cohesive and magnetic properties of iridium oxide clusters adsorbed on graphene.

In this study, we investigated and revealed the electronic properties, geometric structures and binding behavior of small (IrO)n and [Formula: see text] (n = 1-5) clusters within first principles calculations based on the density functional theory. The electronic and magnetic properties of small nanoclusters displayed significant size dependency due to strong quantum confinement effect. Moreover we considered the binding and structural modification of the clusters on graphene surface as a substrate. The cohesive energy per atom of isolated clusters increased with size of the cluster n. This shows that the increase in coordination number results in a more stable nanocluster with increased number of saturated bonds. Pristine (IrO)n and [Formula: see text] clusters presented different structural motives at equilibrium. The ground states of (IrO)n and [Formula: see text] clusters considered in this study were all magnetic except for (IrO)4, [Formula: see text] , and [Formula: see text] . HOMO-LUMO gap EHLG values displayed large variations due to size of the cluster, hence bond saturation. The structural configurations of free standing nanoclusters are slightly modified, when adsorbed on graphene. The adsorption behavior of a cluster on graphene was improved by an applied electric field yielding larger binding energy and larger charger transfer. We observed that electronic and magnetic ground state of the clusters strongly depend on optimized structural configuration for both bare and adsorbed on graphene monolayer.

Tuning the electronic structure of RhX3 (X = Cl, Br, I) nonmagnetic monolayers: effects of charge-injection and external strain.

Atomistic exploration and electronic modification of 2D materials have been a central focus of research since the breakthrough of graphene. In the present study, we introduce and reveal the structure, stability and electronic features of novel RhX3 (X: Cl, Br, I) monolayer systems within the framework of density functional theory. Phonon dispersion spectra and equilibrium molecular dynamics calculations confirm the stability of the phases studied at room and elevated temperatures. The structures are slightly modified because of thermal excitations and maintain their stabilities up to 1000 K. We show that the electronic and magnetic nature of pristine monolayers can be tuned by external effects, i.e. both mechanically and electrically. RhCl3, RhBr3 and RhI3 monolayers are nonmagnetic and indirect-gap semiconductors intrinsically, but display indirect-to-direct band gap transitions at particular strain values. The systems gain a net magnetic moment and are transformed into metals by negative charging. The optical properties, such as the absorption coefficient, optical conductivity, energy loss spectrum, refractive index and extinction coefficient, are also presented. This interesting class of nanomaterials are promising candidates for several applications in nanotechnology and optoelectronics with good thermal stability, mechanical flexibility, and tunable electronic properties.

Structural properties of small semiconductor-binding synthetic peptides.

We have performed exhaustive multicanonical Monte Carlo simulations of three 12-residue synthetic peptides in order to investigate the thermodynamic and structural properties as well as the characteristic helix-coil transitions. In these studies, we employ a realistic model where the interactions between all atoms are taken into account. Effects of solvation are also simulated by using an implicit-solvent model.