Single-zeta Basis Sets Research Articles

Ab Initio Study of Iodine-Doped Carbon Nanotube Conductors

The widespread use of copper in power and data cabling for aircraft, ships, and ground vehicles imposes significant mass penalties and limits cable ampacity. Experimental research has suggested that iodine-doped carbon nanotubes (CNTs) can serve as energy efficient replacements for copper in mass sensitive cabling applications. The high computational costs of ab initio modeling have limited complimentary modeling research on the development of high specific conductance materials. In recent research, the authors have applied two modeling assumptions, single zeta basis sets and approximate geometric models of the CNT junction structures, to allow an order of magnitude increase in the atom count used to model iodine-doped CNT conductors. This permits the ab initio study of dopant concentration and dopant distribution effects, and the development of a fully quantum based nanowire model which may be compared directly with the results of macroscale experiments. The accuracy of the modeling assumptions is supported by comparisons of ballistic conductance calculations with known quantum solutions and by comparison of the nanowire performance predictions with published experimental data. The validated formulation offers important insights on dopant distribution effects and conduction mechanisms not amenable to direct experimental measurement.

Evaluation of Basis Sets with 11-Electron Analytic Effective Core Potentials of Gold for Modeling Molecular Electronic Devices

Three types of 11-electron analytic effective core potentials (ECPs) and their corresponding double-zeta and single-zeta basis sets of gold are evaluated using density functional theory (DFT) calculations. We find that, compared with basis sets derived for use with Hatree-Fock-based Los Alamos (LANL1) and Ermler-Christiansen (EC) ECPs, the DFT-derived Troullier-Martins (TM) ECP together with a single-zeta basis set (TMSZ) is more suitable to describe not only the interaction between gold atoms with a benzene-1,4-dithiolate molecule but also the electronic structure of an infinite 1-dimensional monatomic gold chain. Hence, TMSZ is the best single-zeta basis set with an 11-electron ECP for gold available currently to be used in theoretical calculations on electrical properties of molecular electronic devices with DFT based Green's function method employing a finite analytic basis of local orbitals.

Energy decomposition analyses of diborane.

Diborane as a molecular complex was studied by using a double zeta ab initio MO method and energy decomposition analyses. For diborane, a qualitatively major contribution of HOMO-LUMO transfers was reported by Yamabe et al. on the basis of configuration analyses by using a single zeta basis set. However, no quantitative work on the origin on the complex formation has been reported. In this note, we show that the charge transfer energy is the dominant contributor to the complex formation (2BH3→B2H6). The charge transfer energy and the exchange repulsion are analyzed at the molecular orbital (MO) levels.

Energy decomposition analysis of borazane at the molecular orbital level: Origin of the internal rotation barrier of H3X-YH3.

The origin of the borazane complex, which is composed of NH3 (C3V) and BH3 (C3V), was studied from a quantum-chemical point of view. Calculations were carried out by the ab initio method. A double zeta basis set with polarization functions (4-31G**) and a single zeta basis set (STO-3G) were used. In order to identify the origin of the complex, energy decomposition analyses were carried out at the molecular orbital level. Among the MO-MO interactions which contribute to charge transfer (CT) in the complex formation, the following are significant in the order indicated. [numerical formula] As for the repulsion energy, A1-A1 and valence-valence MO interactions were significant. HOMO-HOMO interaction was dominant in exchange repulsion. Moreover, valence-core MO interaction and E-E MO interaction could not be neglected. On the other hand, it appeared that the internal rotation barrier of the complex might originate from le-le MO interaction. Therefore the same analysis was applied to ethane, disilane, methylsilane, H3B-CH3-and H3N-CH3+. These quantitative analyses showed that the le-le MO interaction is the most important component in the internal rotation barrier of these compounds and complexes.