2014 The cohesion of covalent structures is systematically studied in a simplified Hückel (LCAO) approximation which only allows for one type of interatomic transfer integral for each (03C3 or 03C0) bond. Layers or chains structures with one or two broken 03C3 bonds per atom are compared with saturated or conjugated spn structures. These are also compared with compact metallic sp and with coval...

The effects of Landau-level mixing and finite thickness of the two-dimensional electron gas on the relative stability of Skyrmion and single spin-flip excitations at Landau-level filling factor n51 have been investigated. Landau-level mixing is studied by fixed-phase diffusion Monte Carlo, and finite thickness is included by modifying the effective Coulomb interaction. Both Landau-level mixing ...

Classical density-functional theory is employed to study finite-temperature trends in the relative stabilities of one-component quasicrystals interacting via effective metallic pair potentials derived from pseudopotential theory. Comparing the free energies of several periodic crystals and rational approximant models of quasicrystals over a range of pseudopotential parameters, thermodynamically...

one main group of organic chemistry is related to the aromatic compounds. in the present work, we replaced the ch group of benzene by silicon and nitrogen analogues. then, density functional theory (dft) calculations were carried out for six-membered heterocyclic si-n aromatic rings. full geometry optimizations were performed in gas-phase, and at b3lyp level using 6-311++g(d,p) and cbsb7 basis ...

in this research, we have studied the structural propenies of water. methanol and ethanol surrounding snidewalledcarbon nanotube (swcnt) and mixed of them either and we have investigated the solvent effects onthe relative energies and dipole moment values by ming molecular dynamics simulation. we used differentforce field it, deterrnaned energy and other type of geometrical parameters, on the p...

Molecular pincers or tweezers are designed to hold and release the target molecule. Potential applications involve drug distribution in medicine, environment technologies, or microindustrial techniques. Typically, the binding is dominated by van der Waals forces. Modeling of such complexes can significantly enhance their design; yet obtaining accurate complexation energies by theory is difficul...

stability of the π-π stacking interactions in the ben||n-substituted-coronene complexes was studied using the computational quantum chemistry methods (where ben is benzene and || denotes π-π stacking interaction, and n-substituted-coronene is coronene molecule which substituted with different number of n atoms). the results reveal simultaneous effects of structure and number of heteroatom on th...

stability of the ;-; stacking interactions in the substituted-coronene||cyclooctatetraene complexes wasstudied using the computational quantum chemistry methods (where || denotes ;–; stackinginteraction, and substituted-coronene is coronene which substituted with four similar x groups; x =oh, sh, h, f, cn, and no). there are meaningful correlations between changes of geometricalparameters and t...

To determine the non-bonded interaction energies between Naphthalene and B12N12 Nano ring in different orientations and distances, geometry of molecules with B3LYP method and 6-31g* basis set optimized. Also reactivity and stability of Naphthalene alone and in the presence B12N12 Nano ring checked. Then calculated the NBO, NMR, FREQ, NICS and muliken charge of Naphthalene atoms alone and in the...

To determine the non-bonded interaction energies between Naphthalene and B12N12 Nano ring in different orientations and distances, geometry of molecules with B3LYP method and 6-31g* basis set optimized. Also reactivity and stability of Naphthalene alone and in the presence B12N12 Nano ring checked. Then calculated the NBO, NMR, FREQ, NICS and muliken charge of Naphthalene atoms alone and in the...