arXiv subjects

Boris I. Yakobson

Publications and source records attributed to Boris I. Yakobson.

57 records · Page 4Linked to original sources

arXiv2010

Stability of hydrogenated group-IV nanostructures: magic structures of diamond nanocrystals and Silicon quantum dots

We have developed an effective model to investigate the energetic stability of hydrogenated group-IV nanostructures, followed by validations from first-principles calculations. It is found that the Hamiltonian of X$_{m}$H$_{n}$ (X=C, Si, Ge and Sn) can be expressed analytically by a linear combination of the atom numbers ($m$, $n$), indicating a dominating contribution of X$-$X and X$-$H local interactions. As a result, we explain the stable nanostructures observed experimentally, and provide a reliable and efficient technique of searching the magic structures of diamond nanocrystals(Dia-NCs) and Silicon quantum dots(SiQDs).

cond-mat.mtrl-sci↗

arXiv2010

Graphene edge from A to Z - and the origins of nanotube chirality

The energy of arbitrary graphene edge is derived in analytical form. It contains a "chemical phase shift", determined by the chemical conditions at the edge. Direct atomistic computations support the universal nature of the relationship. Definitive for graphene formation, shapes of the voids or ribbons, this has further important implications for nanotube chirality selection and control by chemical means, at the nucleation stage.

cond-mat.mes-hall↗

arXiv2010

Cones, pringles, and grain boundary landscapes in graphene topology

A polycrystalline graphene consists of perfect domains tilted at angle α to each other and separated by the grain boundaries (GB). These nearly one-dimensional regions consist in turn of elementary topological defects, 5-pentagons and 7-heptagons, often paired up into 5-7 dislocations. Energy G(α) of GB computed for all range 0<=α<=Pi/3, shows a slightly asymmetric behavior, reaching ~5 eV/nm in the middle, where the 5's and 7's qualitatively reorganize in transition from nearly armchair to zigzag interfaces. Analysis shows that 2-dimensional nature permits the off-plane relaxation, unavailable in 3-dimensional materials, qualitatively reducing the energy of defects on one hand while forming stable 3D-landsapes on the other. Interestingly, while the GB display small off-plane elevation, the random distributions of 5's and 7's create roughness which scales inversely with defect concentration, h ~ n^(-1/2)

cond-mat.mtrl-sci↗