Sepiolite is a hydrated magnesium silicate with a microporous and mesoporous structure. The fibrous morphology and the alternating blocks and tunnels along the fiber direction of sepiolite make it an ideal material to sequester a variety of organic and inorganic contaminants. The adsorption of various surfactants by organo sepiolites have been experimentally investigated. How this hydrophobic material adsorbs dye molecules at the atomic level, however, is a great mystery. For this reason, the present study focused on the adsorption of acid azo 57 dye molecules to modified sepiolite. For this purpose, the amenability of sepiolite to remove the anionic textile dye (acid azo red dye 57) was first studied in detail. Additionally, a typical cationic surfactant, hexadecyltrimethylammonium Br (HTAB), was used to modify sepiolite to increase the adsorption capacity. Zeta potential measurements on the sepiolite and the HTAB modified sepiolite were also carried out. Moreover, Density Functional Theory (DFT) studies were performed to understand the mechanism of the adsorption of dye molecules to natural and modified sepiolite surfaces. On the basis of the experimental studies, three general systems were theoretically examined: (i) HTAB molecules on sepiolite basal surfaces to represent four Si tetrahedra, (ii) neutral or charged acid azo red dye 57 molecules on sepiolite basal surfaces to represent four Si tetrahedra, and (iii) HTAB on the surface of neutral or charged acid azo red dye 57 molecules as a substrate. The results clearly indicated good agreement between the experimental studies and the theoretical computational DFT studies. For example, the double layer structure found in experimental studies was also demonstrated in DFT studies and confirmed increased adsorption in the presence of acid azo dye 57.

We outline the scrutiny of the two probe devices formed by placing the nonclassical fullerene molecules CM (20 ≤ M ≤ 30) within semi-infinite gold electrodes using density functional theory. The electronic structure and molecular orbitals of isolated fullerene molecules are broadened to form junction devices with charge injection at zero as well as variegated bias respectively. The molecular junctions thus formed are contemplated for two important electrical constitutions, current, and conductance. These parameters are then elaborated and contemplated for their electronic parameters namely, the density of states, transmission coefficient, molecular orbitals, molecular projected self-consistent Hamiltonian states, electron density, and Mulliken population. We conclude that C20 and C24 fullerene molecule exhibits extremely metallic behavior while others fail to demonstrate such behavior. The molecular device, thus formed, strongly supports the superconductive behavior of the C24 molecule with an ability to easily adapt by modulating its active molecular orbitals under applied potential.

The charge transport properties of anthra-tetrathiophene (ATT) and its brominated and cyanated derivatives (TBATT and TCATT) were investigated by the density functional theory (DFT) coupled with incoherent charge-hopping model. The crystal structure of TCATT is predicted by the dispersion-corrected DFT (DFT-D) method, and those of ATT and TBATT are retrieved from the Cambridge Crystallographic Data Center. The introduction of electron-withdrawing substituents of bromine and cyano decreases the frontier molecular orbital energies but increases the electron affinities, which is beneficial to electron injection and guarantees charge carrier stabilization. The π–π stacking of neighbor molecules with a short distance and large coupling area contributes to the largest transfer integral. The predicted electron mobility of TCATT reaches up to 1.851 cm2/(V·s), indicating that the cyanation of ATT is favorable for improving the electron transport. The angular dependent simulation for electron mobility shows that the electron transport is remarkably anisotropic.

In this article the Cu-Au binding energy in Cu3Au is determined by comparing experimental atom probe tomography (APT) results to simulations. The resulting bonding energy is supported by density functional theory calculations. The APT simulations are based on the Müller-Schottky equation, which is modified to include different atomic neighborhoods and their characteristic bonds. The local environment is considered up to the fifth next nearest neighbors. To compare the experimental with simulated APT data, the AtomVicinity algorithm, which provides statistical information about the positions of the neighboring atoms, is applied. The quality of this information is influenced by the field evaporation behavior of the different species, which is connected to the bonding energies.