Showing papers by "Sven Stafström published in 2001"
TL;DR: A new fullerenelike material consisting of cross-linked nano-onions of C and N that gives high resilience with hardness 7 GPa, Young's modulus 37 GPA, and complete elastic recovery after loading with 0.5 mN to a depth of 75 nm is reported.
Abstract: We report a new fullerenelike material consisting of cross-linked nano-onions of C and N. Growth of the onion shells takes place atom by atom on a substrate surface and yields thin solid films during magnetron sputter deposition. Electron microscopy and energy loss spectroscopy show that the core shell contains up to 20 at. % N corresponding to C(48)N(12) aza-fullerene composition. Nanoindentation of this nanostructured material gives high resilience with hardness 7 GPa, Young's modulus 37 GPa, and complete elastic recovery after loading with 0.5 mN to a depth of 75 nm. Total energy calculations show the stability of C(60-2n)N(2n) aza-fullerenes and suggest the existence of a novel C(48)N(12) molecule.
182 citations
TL;DR: In this paper, the authors investigated polaron dynamics in a system of coupled polymer chains in the presence of an external electric field and identified three different cases for the polaron migration, i.e., the situation in which a polaron reaches a chain end and is scattered to the surrounding chains.
Abstract: The motion of excitations such as polarons is believed to be of fundamental importance for the transport properties of conjugated polymers for the use in, e.g., polymer based LED's. We have investigated polaron dynamics in a system of coupled polymer chains in the presence of an external electric field. In particular, we focus on how a polaron migrates through the polymer lattice, i.e., the situation in which a polaron reaches a chain end and is scattered to the surrounding chains. We show that the outcome of this event strongly depends on the strength of the electric field, and we identify three different cases for the polaron migration.
145 citations
TL;DR: Calculations on poly(G)-poly(C) DNA substantiate a recent report indicating bandlike conduction for this particular form of DNA and show that both guanine and cytosine give rise to conducting channels along the DNA strands.
Abstract: The charge migration process in DNA is subject to a lively debate among researchers at the moment. We have performed calculations on poly(G)-poly(C) DNA which substantiate a recent report indicating bandlike conduction for this particular form of DNA. Our results show that both guanine and cytosine give rise to conducting channels along the DNA strands. The conductivity results from the overlap of the $\ensuremath{\pi}$ orbitals along the base stacks. We also demonstrate that the measured increase of the threshold voltage with temperature in poly(G)-poly(C) DNA is the result of electron localization due to the structural disorder following high temperature.
85 citations
TL;DR: In this paper, the optimal geometries and total energies of a series of aza[60] fullerenes, C60−2nN2n, were calculated by density functional theory using B3LYP/6-31G*.
81 citations
TL;DR: In this paper, the Pariser-Parr-Pople quantum chemical method was used to model the currentvoltage characteristics of individual molecules connected by metallic leads, and the current voltage characteristics of the individual molecules were investigated theoretically.
Abstract: Current-voltage (I-V) characteristics of individual molecules connected by metallic leads are studied theoretically. Using the Pariser-Parr-Pople quantum chemical method to model the molecule enabl ...
53 citations
TL;DR: In this article, the authors used transfer matrices for both chiral and achiral tubes and showed that the localization length scales linearly with the tube diameter but shows no dependence on tube chirality.
Abstract: Anderson localization in carbon nanotubes has been studied using the transfer matrix method. A new method was developed for which transfer matrices could be obtained for both chiral and achiral tubes. The localization length scales Linearly with the tube diameter but shows no dependence on tube chirality. The conductance in the nanotubes can be significantly altered by functionalization, an effect that could make them applicable as sensors. DOI: 10.1103/PhysRevB.63.113406.
30 citations
TL;DR: Investigation of polaron dynamics in a system of coupled polymer chains in the presence of an external electric field focuses on how a polaron migrates through the polymer lattice, and shows that the outcome of this event strongly depends on the strength of the electric field.
20 citations
TL;DR: In this article, Hartree-Fock integrals are used to describe the attractive part of the interaction of loosely bonded π-electron systems of various orientations, such as interchain hoppings in conjugated polymers or those between two-dimensional graphitic sheets.
Abstract: Parameters for effective hopping integrals are extracted from ab initio Hartree–Fock calculations on model systems These effective hoppings can be used to describe the attractive part of the interaction of loosely bonded π-electron systems of various orientations, such as interchain hoppings in conjugated polymers or those between two-dimensional graphitic sheets © 2001 John Wiley & Sons, Inc Int J Quantum Chem 84: 216–225, 2001
14 citations
TL;DR: In this paper, a theoretical investigation of phenylene ethynylene macrocycles and oligomers aggregation was carried out, and two types of stacked supramolecular organization were investigated at the MP2 level.
13 citations
TL;DR: In this paper, the relative stability between helices and chains formed by phenylene ethynylene oligomers connected in ortho and meta positions of the phenyl rings was investigated at the second order Moller-Plesset perturbation theory level.
1 citations
18 Oct 2001