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Xiang-Feng Zhou

Bio: Xiang-Feng Zhou is an academic researcher from Yanshan University. The author has contributed to research in topics: Ab initio & Graphene. The author has an hindex of 27, co-authored 82 publications receiving 4479 citations. Previous affiliations of Xiang-Feng Zhou include State University of New York System & Nanjing University.


Papers
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Journal ArticleDOI
18 Dec 2015-Science
TL;DR: At Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling that are consistent with predictions of a highly an isotropic, 2D metal.
Abstract: At the atomic-cluster scale, pure boron is markedly similar to carbon, forming simple planar molecules and cage-like fullerenes. Theoretical studies predict that two-dimensional (2D) boron sheets will adopt an atomic configuration similar to that of boron atomic clusters. We synthesized atomically thin, crystalline 2D boron sheets (i.e., borophene) on silver surfaces under ultrahigh-vacuum conditions. Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling. Unlike bulk boron allotropes, borophene shows metallic characteristics that are consistent with predictions of a highly anisotropic, 2D metal.

1,873 citations

Journal ArticleDOI
TL;DR: In this paper, a novel 2D boron structure with nonzero thickness was proposed based on an ab initio evolutionary structure search, which is considerably lower in energy than the recently proposed $\ensuremath{\alpha}$-sheet structure and its analogues.
Abstract: It has been widely accepted that planar boron structures, composed of triangular and hexagonal motifs are the most stable two-dimensional (2D) phases and likely precursors for boron nanostructures. Here we predict, based on an ab initio evolutionary structure search, a novel 2D boron structure with nonzero thickness, which is considerably, by $50\text{ }\text{ }\mathrm{meV}/\mathrm{atom}$, lower in energy than the recently proposed $\ensuremath{\alpha}$-sheet structure and its analogues. In particular, this phase is identified for the first time to have a distorted Dirac cone, after graphene and silicene the third elemental material with massless Dirac fermions. The buckling and coupling between the two sublattices not only enhance the energetic stability, but also are the key factors for the emergence of the distorted Dirac cone.

504 citations

Journal ArticleDOI
TL;DR: The electronic structure of phagraphene has distorted Dirac cones, which are lower in energy than most of the predicted 2D carbon allotropes due to its sp(2)-binding features and density of atomic packing comparable to graphene.
Abstract: Using systematic evolutionary structure searching we propose a new carbon allotrope, phagraphene [fae'graefi:n], standing for penta-hexa-hepta-graphene, because the structure is composed of 5-6-7 carbon rings. This two-dimensional (2D) carbon structure is lower in energy than most of the predicted 2D carbon allotropes due to its sp(2)-binding features and density of atomic packing comparable to graphene. More interestingly, the electronic structure of phagraphene has distorted Dirac cones. The direction-dependent cones are further proved to be robust against external strain with tunable Fermi velocities.

458 citations

Journal ArticleDOI
TL;DR: It is shown that the presence of He atoms causes strong electron localization and makes this material insulating, and it is predicted that the existence of Na2HeO with a similar structure at pressures above 15 GPa is predicted.
Abstract: Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na2He, which has a fluorite-type structure and is stable at pressures >113 GPa. We show that the presence of He atoms causes strong electron localization and makes this material insulating. This phase is an electride, with electron pairs localized in interstices, forming eight-centre two-electron bonds within empty Na8 cubes. We also predict the existence of Na2HeO with a similar structure at pressures above 15 GPa.

264 citations

Journal ArticleDOI
TL;DR: The simulated x-ray diffraction pattern, density, and bulk modulus of Cco-C(8) are in good accordance with the experimental data on structurally undetermined superhard carbon recovered from cold compression of carbon nanotube bundles.
Abstract: A novel carbon allotrope of C-centered orthorhombic ${\mathrm{C}}_{8}$ ($\mathrm{Cco}\mathrm{\text{\ensuremath{-}}}{\mathrm{C}}_{8}$) is predicted by using a recently developed particle-swarm optimization method on structural search. $\mathrm{Cco}\mathrm{\text{\ensuremath{-}}}{\mathrm{C}}_{8}$ adopts a $s{p}^{3}$ three-dimensional bonding network that can be viewed as interconnected $(2,2)$ carbon nanotubes through 4- and 6-member rings and is energetically more favorable than earlier proposed carbon polymorphs (e.g., $M$ carbon, $\mathrm{bct}\mathrm{\text{\ensuremath{-}}}{\mathrm{C}}_{4}$, $W$ carbon, and chiral ${\mathrm{C}}_{6}$) over a wide range of pressures studied (0--100 GPa). The simulated x-ray diffraction pattern, density, and bulk modulus of $\mathrm{Cco}\mathrm{\text{\ensuremath{-}}}{\mathrm{C}}_{8}$ are in good accordance with the experimental data on structurally undetermined superhard carbon recovered from cold compression of carbon nanotube bundles. The simulated hardness of $\mathrm{Cco}\mathrm{\text{\ensuremath{-}}}{\mathrm{C}}_{8}$ can reach a remarkably high value of 95.1 GPa, such that it is capable of cracking diamond.

216 citations


Cited by
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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: The unique advances on ultrathin 2D nanomaterials are introduced, followed by the description of their composition and crystal structures, and the assortments of their synthetic methods are summarized.
Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

3,628 citations

01 Jan 2011

2,117 citations

Journal ArticleDOI
TL;DR: This paper presents a probabilistic procedure for estimating the polymethine content of carbon dioxide using a straightforward two-step procedure, and shows good results in both the stationary and the liquid phase.
Abstract: Liming Dai,*,†,‡ Yuhua Xue,†,‡ Liangti Qu,* Hyun-Jung Choi, and Jong-Beom Baek* †Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China School of Energy and Chemical Engineering/Center for Dimension-Controllable Covalent Organic Frameworks, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon, Ulsan, 689-798, South Korea

1,967 citations