Layered Double Hydroxides as Systems for Capturing Small-Molecule Air Pollutants: A Density Functional Theory Study.

Air pollutants are usually formed by easily spreading small molecules, representing a severe problem for human health, especially in urban centers. Despite the efforts to stem their diffusion, many diseases are still associated with exposure to these molecules. The present study focuses on modeling and designing two-dimensional systems called Layered Double Hydroxides (LDHs), which can potentially trap these molecules.

Adsorption of Polylactic-co-Glycolic Acid on Zinc Oxide Systems: A Computational Approach to Describe Surface Phenomena.

Zinc oxide and polylactic-co-glycolic acid (ZnO-PLGA) nanocomposites are known to exhibit different biomedical applications and antibacterial activity, which could be beneficial for adding to wound dressings after different surgeries. However, possible cytotoxic effects along with various unexpected activities could reduce the use of these prominent systems. This is correlated to the property of ZnO, which exhibits different polymeric forms, in particular, wurtzite, zinc-blende, and rocksalt.

Towards graphene-based asymmetric diodes: a density functional tight-binding study.

Self-consistent charge density functional tight-binding (DFTB) calculations have been performed to investigate the electrical properties and transport behavior of asymmetric graphene devices (AGDs). Three different nanodevices constructed of different necks of 8 nm, 6 nm and 4 nm, named Graphene-N8, Graphene-N6 and Graphene-N4, respectively, have been proposed. All devices have been tested under two conditions of zero gate voltage and an applied gate voltage of +20 V using a dielectric medium of 3.

The Effect of Y Doping on Monoclinic, Orthorhombic, and Cubic Polymorphs of HfO: A First Principles Study.

HfO can assume different crystalline structures, such as monoclinic, orthorhombic, and cubic polymorphs, each one characterized by unical properties. The peculiarities of this material are also strongly related to the presence of doping elements in the unit cell. Thus, the present paper has the main purpose of studying and comparing twelve different systems characterized by diverse polymorphs and doping percentages.

PBEsol/HSE functional: a promising candidate for vanadium dioxide (B) characterization.

A VO(B) polymorph has been thoroughly investigated by means of density functional theory (DFT) calculations to evaluate the structure, Raman spectrum, cohesive energy, phonon band structure, an delectronic and optical properties. Among the computed Raman modes, eight of them have been assigned to the VO(B) structure in full agreement with the corresponding experimental spectra. The minimized structure of the VO(B) polymorph indicated the presence of negative frequencies in its phonon dispersion curves, confirming the dynamic instability of this material.

Insights into first-principles characterization of the monoclinic VO(B) polymorph DFT + U calculation: electronic, magnetic and optical properties.

We have studied the structural, electronic, magnetic, and optical properties of the VO(B) polymorph using first-principles calculations based on density functional theory (DFT). This polymorph was found to display four optimized structures namely VO(B), VO(B), VO(B), and VO(B) using the generalized gradient approximation (GGA) PBE exchange-correlation functional by including/excluding van der Waals interaction. Our derivation provides a theoretical justification for adding an on-site Coulomb value in the conventional DFT calculations to allow a direct comparison of the two methods.

The Role of Zr on Monoclinic and Orthorhombic HfZrO Systems: A First-Principles Study.

HfO shows different polymorphs, including monoclinic and orthorhombic ones, that exhibit singular properties. Moreover, the character of HfO is also influenced by the Zr atoms as a doping agent. Here, an extensive study of the monoclinic and the orthorhombic polymorphs of HfO, HfZrO, and HfZrO is reported.

Electronic, optical, mechanical, and thermal properties of diphenylacetylene-based graphyne nanosheet using density functional theory.

In this paper, the structural stability, electronic, optical, mechanical, and thermal properties of diphenylacetylene-based graphyne (DPAG) nanosheet are investigated using first-principle calculations based on density functional theory (DFT). The absolute value of the calculated cohesive energy reveals that DPAG nanosheet is a structurally stable two-dimensional material. Also, in the results of phononic dispersion curves, the absence of imaginary frequencies confirms the dynamic stability of this novel material.

On-surface synthesis of extended linear graphyne molecular wires by protecting the alkynyl group.

In this paper we report on the use of an Ullmann-like aryl halide homocoupling reaction to obtain long Graphyne Molecular Wires (GY MWs) organized in dense, ordered arrays. Instead of using highly reactive terminal alkynes, we resort to a precursor wherein the acetylenic functional group is internal, namely protected by two phenyl rings, each bearing a Br atom in the para position to allow for linear homocoupling. In addition, two further factors concur with the production of dense and highly ordered arrays of very long GY MWs, namely the geometric compatibility between the substrate and both the organometallic intermediates and the final polymeric products of the synthesis, coupled with the presence of surface-adsorbed bromine atoms separating the MWs, which minimize inter-wire cross-linking secondary reactions.