We use ab initio total-energy calculations to predict the existence of polarons in semiconducting carbon nanotubes (CNTs). We find that the CNTs' band edge energies vary linearly and the elastic energy increases quadratically with both radial and with axial distortions, leading to the spontaneous formation of polarons. Using a continuum model parametrized by the ab initio calculations, we estim...

Gas-phase activation energies were calculated for three lithium enolate reactions by using several different ab initio and density functional theory (DFT) methods to determine which levels of theory generate acceptable results. The reactions included an aldol-type addition of an enolate to an aldehyde, a proton transfer from an alcohol to a lithium enolate, and an S(N)2 reaction of an enolate w...

This article addresses a fundamental problem faced by the ab initio community: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a novel, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the development, implementation, and dissemination of new ab initio techniques to th...

Studies of 6He beta decay along with tritium can play an important role in testing ab initio nuclear wave-function calculations and may allow for fixing low-energy constants in effective-field theories. Here, we present an improved determination of the 6He half-life to a relative precision of 3×10(-4). Our value of 806.89±0.11(stat)(-0.19syst)(+0.23)  ms resolves a major discrepancy between pre...

Fakultät für Chemie der Universität, Postfach 8640, D-4800 Bielefeld 1, FRG Z. Naturforsch. 40b, 1149-1151 (1985); received May 20, 1985 Bonding, Ab initio Double Zeta Calculations Ab initio SCF calculations at a double-^ level were performed on the cations N (PH 3)2+ and P(PH 3)2+. Although both structures are isoelectronic, their bonding situation is different. The latter corresponds to a dip...

Results of detailed calculations for SrTiOs (100) surface relaxation and the electronic structure for the two different terminations (SrO and TiO2) are discussed. These are based on ab initio Hartree-Fock (HF) method with electron correlation corrections and Density Functional Theory (DFT) with different exchange-correlation functionals, including hybrid (B3PW, B3LYP) exchange techniques. Resul...

This article addresses a fundamental problem faced by the ab initio community: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a novel, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the development, implementation, and dissemination of new ab initio techniques to th...

The F(2)+CH(3)SCH(3) reaction was studied with crossed molecular beam techniques and high level ab initio calculations. Significant reactivity was observed even at low collision energies, consistent with the negligible barrier height obtained from the ab initio calculations. All experimental findings are consistent with a weakly bound reaction intermediate of F-F-S(CH(3))(2) structure, which po...

For the initially formed C3H2 collision complexes of molecular beam experiments ab initio calculations are presented. Resolving energetics and properties of these intermediates is essential for the understanding of the reaction of C~P! with C2H2 to form interstellar cyclic and linear isomers of C3H. Computed reaction energies agree with results from molecular beam experiments. The combination o...