D.-B. Zhang
University of Minnesota
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by D.-B. Zhang.
Applied Physics Letters | 2010
I. Nikiforov; D.-B. Zhang; Richard D. James; Traian Dumitrică
Objective molecular dynamics is used to systematically investigate elastic bending in carbon nanotubes up to 4.2 nm in diameter. A contrasting behavior is revealed: While single-wall tubes buckle in a gradual way, with a clear intermediate regime before they fully buckle, multiwalled tubes with closed cores exhibit a rate- and size-independent direct transition to an unusual wavelike mode with a 1 nm characteristic length. This rippling mode has a nearly-linear bending response and causes a ∼35% reduction in the stiffness of the thickest multiwalled tubes.
Journal of Chemical Physics | 2008
D.-B. Zhang; M. Hua; Traian Dumitrică
The stability of the most promising ground state candidate Si nanowires with less than 10 nm in diameter is comparatively studied with objective molecular dynamics coupled with nonorthogonal tight-binding and classical potential models. The computationally expensive tight-binding treatment becomes tractable due to the substantial simplifications introduced by the presented symmetry-adapted scheme. It indicates that the achiral polycrystalline of fivefold symmetry and the wurtzite wires of threefold symmetry are the most favorable quasi-one-dimensional Si arrangements. Quantitative differences with the classical model description are noted over the whole diameter range. Using a Wulff energy decomposition approach it is revealed that these differences are caused by the inability of the classical potential to accurately describe the interaction of Si atoms on surfaces and strained morphologies.
Physical Review Letters | 2014
D.-B. Zhang; Tao Sun; Renata M. Wentzcovitch
We use a hybrid strategy to obtain anharmonic frequency shifts and lifetimes of phonon quasiparticles from first principles molecular dynamics simulations in modest size supercells. This approach is effective irrespective of crystal structure complexity and facilitates calculation of full anharmonic phonon dispersions, as long as phonon quasiparticles are well defined. We validate this approach to obtain anharmonic effects with calculations in MgSiO3 perovskite, the major Earth forming mineral phase. First, we reproduce irregular thermal frequency shifts of well characterized Raman modes. Second, we combine the phonon gas model (PGM) with quasiparticle frequencies and reproduce free energies obtained using thermodynamic integration. Combining thoroughly sampled quasiparticle dispersions with the PGM we then obtain first-principles anharmonic free energy in the thermodynamic limit (N→∞).
Physical Review B | 2009
D.-B. Zhang; Richard D. James; Traian Dumitrica
Physical Review Letters | 2010
D.-B. Zhang; Traian Dumitrică; Gotthard Seifert
Physical Review B | 2014
Tao Sun; D.-B. Zhang; Renata M. Wentzcovitch
Physical Review B | 2011
A. Mittal; D.-B. Zhang; C. Teresi; T. Dumitricǎ; K. A. Mkhoyan
Journal of Physical Chemistry Letters | 2011
Ilia Nikiforov; D.-B. Zhang; Traian Dumitrică
Physical Review B | 2012
D.-B. Zhang; Traian Dumitrică
Journal of Chemical Physics | 2011
D.-B. Zhang; Traian Dumitrică