Hu-Jun Qian

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Resonance Raman scattering is used to determine the radial breathing mode ͑RBM͒ frequency ͑␻ RBM ͒ dependence on tube diameter ͑d t ͒ for single-wall carbon nanotubes ͑SWNTs͒. We establish experimentally the ␻ RBM = 227.0/ d t as the fundamental relation for pristine SWNTs. All the other RBM values found in the literature can be explained by an upshift in(More)
IBIsCO is a parallel molecular dynamics simulation package developed specially for coarse-grained simulations with numerical potentials derived by the iterative Boltzmann inversion (IBI) method (Reith et al., J Comput Chem 2003, 24, 1624). In addition to common features of molecular dynamics programs, the techniques of dissipative particle dynamics (Groot(More)
In this contribution, we apply a microscopic technique that relies on the enhanced electric field near a sharp, laser-irradiated metal tip that acts as a highly confined light source. The tip is used for the local excitation of the optical response of single-walled carbon nanotubes (SWNT) deposited on glass. We demonstrate photoluminescence and Raman(More)
Multiscale modeling of a polymeric system is a challenging task in polymer physics. Here we introduce a bottom-up and then top-down scheme for the simulation of polyethylene (PE). The coarse-grained numerical potential for PE is derived through an automatic updating program by mapping its radial distribution function (RDF) from the Lowe-Andersen temperature(More)
Comprehensive three-dimensional dissipative particle dynamics simulations are carried out to elucidate the diffusion mechanism of a strongly adsorbed polymer chain on a solid surface in dilute solutions. We find Rouse and reptation dynamics for polymer chain diffusing on smooth and rough surfaces (with obstacles or sticking points), respectively. Combining(More)
GALAMOST [graphics processing unit (GPU)-accelerated large-scale molecular simulation toolkit] is a molecular simulation package designed to utilize the computational power of GPUs. Besides the common features of molecular dynamics (MD) packages, it is developed specially for the studies of self-assembly, phase transition, and other properties of polymeric(More)
Quantum chemical molecular dynamics simulations of graphene nucleation on the Ni(111) surface show that graphene creates its own step-edge as it forms. This "step-edge self-assembly" is driven by the formation of thermodynamically favorable Ni-C σ-bonds at the graphene edge. This dynamic aspect of the Ni(111) catalyst is in contrast to the commonly accepted(More)
Ab initio coupled cluster and density functional theory studies of atomic hydrogen addition to the central region of pyrene and coronene as molecular models for graphene hydrogenation were performed. Fully relaxed potential energy curves (PECs) were computed at the spin-unrestricted B3LYP/cc-pVDZ level of theory for the atomic hydrogen attack of a center(More)
Quantum chemical molecular dynamics (QM/MD) simulations of ensembles of C(2) molecules on the Ni(111) terrace show that, in the absence of a hexagonal template or step edge, Haeckelite is preferentially nucleated over graphene as a metastable intermediate. The nucleation process is dominated by the swift transition of long carbon chains toward a fully(More)
The influence of polymerization on the phase separation of binary immiscible mixtures has been investigated by the dissipative particle dynamics simulations in two dimensions. During polymerization, the bulk viscosity increases, which consequently slows down the spinodal decomposition process. The domain size growth is monitored in the simulations. The(More)