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The electronic, optical, and photocatalytic properties of ribbon-like Bi 2 S 3 have been investigated at different external applied pressures 0–9.18 GPa using the density functional theory (DFT) method within the generalized gradient approximation. The electronic structures and optical properties indicate that ribbon-like Bi 2 S 3 is p-type semiconductor with indirect band gap. The photocatalytic activity of ribbon-like Bi 2 S 3 decreases with increasing in the hydrostatic pressure. Based on band structure and density of states (DOS) calculations the conduction and valence bands of ribbon-like Bi 2 S 3 are mostly derived from Bi 6p and S 3p states. The charge density distribution indicates that the nature of Bi–S bonds is covalent. The calculated optical properties indicate that ribbon-like Bi 2 S 3 is ultra violet light response photocatalyst. Calculated position of valence band and conduction band potentials indicate that ribbon-like Bi 2 S 3 has strong oxidation ability for water splitting into O 2 , but for water splitting into H 2 and subsequently increasing of photocatalytic activity co-catalyst should be added.

Theoretical study of exohedral chemical functionalization of C48B6N6 with NH3 molecules has been investigated using DFT. It was found that NH3 molecule can be chemically adsorbed on boron sites of C48B6N6, with a charge transfer from NH3 to C48B6N6. Adsorption energy and the quantity of electron charge transfer from latest adsorbed ammonia to C48B6N6 decreased with increasing in the adsorbed NH3 molecules. Despite the strong adsorption energies, electronic properties of C48B6N6 is preserved after modification(s) with NH3 molecule(s) and chemical modification of C48B6N6 with NH3 molecules can be viewed as some kind of safe modification.

The electronic structures and physical properties of zigzag BC2N (n,0; n = 4–10) and armchair BC2N (n,m; n = m = 4–10) nanotubes (type III) are studied by using density functional theory with the generalized gradient approximation. From a comparison of the binding energies, it is inferred that in the large diameter BC2N nanotubes, the zigzag form is thermally more stable than the armchair form. BC2N nanotubes (with the exception of (4,0) which is conductor) are gapless semiconductors. Depend on the chirality index, the zigzag forms of BC2N nanotubes have narrower band gap than the armchair form. Semiconductor character in the studied BC2N nanotubes is due to contribution of p electrons in the Fermi level. Mulliken population analyses show that significant amounts of electron charge are transferred between atoms; which suggests the existence of polar covalent bonds in the BC2N nanotubes.

The electron transport properties of furan, thiophene and selenophene dithiols based molecular wires through two electrodic systems using non-equilibrium Green’s functions technique (NEGF) are investigated. The electron transport of the above systems is systematically studied by analysis of transmission function, density of states, current–voltage characteristics, and conductance of the systems. The maximum current is occurred at the vicinity of 2.0 V and the values are 90.37, 98.82 and 100.31 μA for furan, thiophene and selenophene dithiols, respectively. These results can be attributed to the molecular projected self consistent Hamiltonian (MPSH) of two electrodic systems with different molecules at different bias voltage and also to quality of resonance of π electrons of heterocyclic ring. We can foresee that the furan, thiophene, and selenophene dithiols can be applied at electronic devices because of switching the high and low current.

Two models of (10, 0) boron nitride nanotubes (BNNTs), perfect and Ammonia-attached, were studied in order to evaluate the influence of NH 3 -attaching on the B-11 and N-15 nuclear magnetic resonance in the (10, 0) boron-nitride nanotube (BNNT) for the first time. At first, based on density functional theory (DFT) each of the structures was optimized using B3LYP/6-31G (d) model chemistry. At the next step, the chemical-shielding (CS) tensors were calculated using the B3LYP/6-31G (d, p) level of theory in both of the relaxed forms and were converted to experimentally measurable nuclear magnetic resonance (NMR) parameters, i.e. chemical-shielding isotropic (CSI) and chemical-shielding anisotropic (CSA). Our calculation revealed that in the NH 3 -attached BNNT (the most stable model) the B atom chemically bonded to the NH 3 molecule has the largest chemical-shielding isotropic (CSI) and the smallest chemical-shielding anisotropic (CSA) values among the other boron nuclei. Additionally, the NMR parameters of those nuclei directly bonded to the boron dramatically change while those of the other B nuclei remain almost unchanged.