16,069 research outputs found
Asymptotic Correction Schemes for Semilocal Exchange-Correlation Functionals
Aiming to remedy the incorrect asymptotic behavior of conventional semilocal
exchange-correlation (XC) density functionals for finite systems, we propose an
asymptotic correction scheme, wherein an exchange density functional whose
functional derivative has the correct (-1/r) asymptote can be directly added to
any semilocal density functional. In contrast to semilocal approximations, our
resulting exchange kernel in reciprocal space exhibits the desirable
singularity of the type O(-1/q^2) as q -> 0, which is a necessary feature for
describing the excitonic effects in non-metallic solids. By applying this
scheme to a popular semilocal density functional, PBE [J. P. Perdew, K. Burke,
and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996)], the predictions of the
properties that are sensitive to the asymptote are significantly improved,
while the predictions of the properties that are insensitive to the asymptote
remain essentially the same as PBE. Relative to the popular model XC potential
scheme, our scheme is significantly superior for ground-state energies and
related properties. In addition, without loss of accuracy, two closely related
schemes are developed for the efficient treatment of large systems.Comment: 7 pages, 2 figures, 2 tables, supplementary material not include
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Surface-Only Simulation of Fluids
Surface-only simulation methods for fluid dynamics are those that perform computation only on a surface representation, without relying on any volumetric discretization. Such methods have superior asymptotic complexity in time and memory than the traditional volumetric discretization approaches, and thus are more tractable for simulation of complex fluid phenomena. Although for most computer graphics applications and many engineering applications, the interior flow inside the fluid phases is typically not of interest, the vast majority of existing numerical techniques still rely on discretization of the volumetric domain. My research first tackles the mesh-based surface tracking problem in the multimaterial setting, and then proposes surface-only simulation solutions for two scenarios: the soap-films and bubbles, and the general 3D liquids. Throughout these simulation approaches, all computation takes place on the surface, and volumetric discretization is entirely eliminated
Evolution of pore structure, submaceral composition and produced gases of two Chinese coals during thermal treatment
This research was funded by the Research Program for Excellent Doctoral Dissertation Supervisor of Beijing (grant no. YB20101141501), the Fundamental Research Funds for Central Universities (grant no. 35832015136) and Key Project of Coal-based Science and Technology in Shanxi Province-CBM accumulation model and reservoir evaluation in Shanxi province (grant no. MQ2014-01).Peer reviewedPostprin
Opinion dynamics on directed small-world networks
In this paper, we investigate the self-affirmation effect on formation of
public opinion in a directed small-world social network. The system presents a
non-equilibrium phase transition from a consensus state to a disordered state
with coexistence of opinions. The dynamical behaviors are very sensitive to the
density of long-range interactions and the strength of self-affirmation. When
the long-range interactions are sparse and individual generally does not insist
on his/her opinion, the system will display a continuous phase transition, in
the opposite case with high self-affirmation strength and dense long-range
interactions, the system does not display a phase transition. Between those two
extreme cases, the system undergoes a discontinuous phase transition.Comment: 6 pages, 5 figure
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