Papers by Keyword: Dipole Moment

Abstract: The study involves treating various metal complexes in "gas phase" with the prepared ligands (2,6-bis (((1-octyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₁), 2,6-bis (((1-decyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₂) and 2,6-bis (((1-dodecyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine (L₃). Two different types of programs, the Hyperchem-8 and Gaussian programs, were used to study the theory. The heat of formation (ΔH^of), binding energy (ΔEb), and dipole moment (µ) for free ligands and some metal complexes were calculated using semi-experimental and molecular mechanics in the Hyper-8 program using a variety of computational techniques including ZINDO/1, PM3, and AMBER methods at room temperature. The created complexes are discovered to be more stable than the free ligands. For proper location of the molecules, Hyperchem.-8 was used to determine the vibration frequencies for (FT-IR) and electronic transitions, as well as electrostatic potential, HOMO, and LUMO energy. The compatibility of the theoretical and experimental findings was highlighted. In order to calculate the geometry optimization, dipole moment (µ), total energy, electrostatic potential, LUMO, and HOMO, a Gaussian algorithm employing a semi-empirical (PM3) approach was utilized. "Vibration spectra of free ligands are calculated and noted that they agreed well with those values experimentally found" diagnosis with a higher level of capacity to effectively diagnose packages. Using a technique like ZINDO/S, the electronic transitions for the ligand were also computed.

Abstract: In this study, we have examined, under the influence of an electric field applied along the z-direction, the binding energy Stark-shift, the dipole moment and the polarizability of a confined shallow donor impurity in GaAs conical-shaped quantum dots (CSQD). With square infinite confinement system, the calculations are based on the approximation of the effective mass by using the finite difference method. Our results show that increasing the radius of the CSQD structure and the electric field intensity increases the Stark shift binding energy and it has a mixed behavior as a function of the impurity position. Furthermore, the polarizability and the dipole moment vary in a quasi-linear way as a function of the dot radius and they follow a decreasing function as a function of the electric field intensity. These two physical parameters have a double behavior, they decrease with the position of the impurity in the strong confinement regime and they increase in the top regions of the quantum dot. These results provide a lot of information about the behavior of the electronic wave function which give more interesting ideas for the fabrication of optoelectronic devices.

Abstract: The lowest-energy geometrical structures of a cluster containing 55 atoms were searched by using the Density Functional Tight Binding (DFTB) combined with unbiased global optimization genetic algorithms (GAs) method. Two lowest-energy structures were obtained for the Si₅₅ cluster with the appearance of “Y shape” and “like-spherical shape” configurations. The configuration dependence average energy, highest occupied and lowest unoccupied molecular (HOMO-LUMO) gap, electron transfer and molecular dipole moment were also discussed in details for this cluster.

Abstract: The experimental data on efficiencies of a series of 7 ureides and 5 acetylides as inhibitors (IN) of corrosion of mild steel in Postgate B media compared to quantum chemical data; the following descriptors found to be essential to describe the inhibitive properties under given conditions: energies of the boundary molecular orbitals (HOMO and LUMO) and dipole moment. The inhibitive properties of the chosen ureides under given conditions are based on electron donating rather than accepting properties of their molecules. PM/3 method was found to be preferable compared to other quantum chemical methods used (i.e., MNDO, AM/1), and even non-empiric ab initio methods because it is found to be more helpful in explaining the mechanism of inhibitive action of organic species.

Abstract: Geometric structure of W_mB_n(m+n7) clusters are optimized by using the density functional theory at the B3LYP/LANL2DZ level. For the ground state configurations, polarizability and dipole moment are analyzed. The calculated results show that: Δα varies with W atom which present turbulence change; W₂B₃ cluster is nonpolar, WB₅ cluster has the strongest polarity, W₅B₂ cluster has the weakest polarity, symmetry of clusters influence polarizabilities and dipole moment.

Abstract: We describe the non-harmonic dipole moment resulting of the interaction between a set of nanoparticles randomly distributed with a linear polarized plane wave. The study is performed by considering its structural parameters as function of time establishing a mechanical analogy with a spring less system. The simplest case occurs for two nanoparticles and the Mathieu differential equation describes the dipole interaction, from which interesting resonance effects are predicted. We show that an effective refractive index depending of time is obtained having the possibility to take negative values which offers interesting applications in the development of metamaterials. Finally associating a catastrophe function for the phase function, during the emission process we are able to describe the width of the frequency spectrum. The theoretical are well agree with experimental results previously reported in the optical literature.

Abstract: We investigated the chemical sensing mechanism of epitaxial graphene grown on 6H-SiC (0001) to different polar solvents and their behavior at higher temperatures. We show that at 300 K the sensitivity of the graphene sensor increases exponentially with the dipole moment of a solvent and decreases significantly as the temperature increased to 425 K. Using electrical measurements, we also show that graphene can effectively discriminate between polar protic and polar aprotic solvents with the shift in device electrical resistance at 300 K.

Abstract: The unperturbed dimensions of symmetric polymers are investigated by an improved conformational statistic method considering effect of side groups. Following the deduced formulas, the characteristic ratios of mean-square radius of gyration for poly(dimethylsilmethylene) (PDMSM), poly(vinylidene fluoride)(PVDF), polyphosphate(PP), polyoxymethylene(POM) and poyisobutylene (PIB) are calculated 0.69, 0.84, 1.23, 0.85 and 1.18, respectively. The ratios of mean-square dipole moment are 0.35, 0.48, 0.59 and 0.79 for PP, PDMSM, POM and PVDF long chains, respectively. From comparing the ratios of five polymers, it is found that the consideration of side groups for short chains is exceedingly important in calculation of characteristic quantity, especially for the inorganic polymers with heteroatom. PVDF are excellent in flexibility and electric dipole properties. The temperature characters of PIB are concerned closely with its conformational energy.