Size dependent structural and electronic properties of MgO nanotube clusters

Abstract

MgO nanotube clusters which cross sections are composed of two-, three-, four-, and five-membered rings are constructed and studied by the density functional theory at B3LYP/6-31G(d) level. The variations of bond length present anisotropic effect. Three-membered ring nanotube cluster is the most stable tube among these MgO isomers. Mixed covalent and ionic bonding always exists in MgO nanotube clusters. With increasing length of MgO nanotube clusters, the averaged atomic charge increases, and converge to 1.227; the s-p separation of O bands decreases; whereas energy gap nearby frontier orbitals present dramatic difference corresponding to various structure family. It is possible that MgO nanotube clusters show electronic properties of semiconductor. An interpretation for MgO nanotube clusters fabricated by simply thermal methods is proposed. The structural and electronic properties of MgO nanotube clusters are discussed systematically in details.

Structure determination of neutral MgO clusters—hexagonal nanotubes and cages

“…For other cluster compositions often more cube-like structures are predicted, but there is no common agreement on their structures in the literature yet. Quantum chemical methods [22][23][24][25][26][27] in combination with global optimization approaches have to our knowledge not yet been systematically applied to neutral MgO clusters of different sizes. Only for the alkaline halide clusters (LiF) n , which are assumed to behave very similar to MgO clusters, 15 simulated annealing at an ab initio level has been performed for n = 1-8.…”

Linear Relationship between Weighted-Average Madelung Constants and Density Functional Theory Energies for MgO Nanotubes

“…Indeed, lattice and cohesive energies can be accurately modeled using Born–Mayer-like potential functions. However, the bonding occurring within nanostructures of these materials can be less straightforward because covalent interactions can become significant . Quantum mechanical calculations have been adopted to attack this issue, with DFT methods being the most popular.…”

Effect of the intramolecular hydrogen bond on the spectral and optical properties in chitosan oligosaccharide

“…Chitosan oligosaccharide is a helical structure; the change of the bond lengths, bond angles and IR spectra of active groups are complicated. The result is obviously different from inorganic nanotubes and organic oligopeptides chain [18,19,21]. Inorganic nanotubes have no group to form hydrogen bond, and single oligopeptide chain does not have typical intramolecular hydrogen bond [21].…”

“…Nanosystem has its own special properties, such as the size effect and the anisotropy [14][15][16][17]. Liang Chen et al [18][19][20] studied the IR frequency shift of SiO 2 and MgO inorganic nanotube clusters in the growth process, and they found this kind of nanomaterial exist obvious size effect and nonlinear optical properties. In the previous work, we also research the growth process of oligopeptide chains about the physical and chemical properties, especially the size effect of infrared spectra has been discussed [21][22][23][24].…”