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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
M4@Si28 (M=Al,Ga) Metal-Encapsulated Tetrahedral Silicon Fullerene, Yi Gao, Xiao Cheng Zeng
M4@Si28 (M=Al,Ga) Metal-Encapsulated Tetrahedral Silicon Fullerene, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
It is known that silicon fullerenes cannot maintain perfect cage structures like carbon fullerenes. Previous density-functional theory calculations have shown that even with encapsulated species, nearly all endohedral silicon fullerenes exhibit highly puckered cage structures in comparison with their carbon counterparts. In this work, we present theoretical evidences that the tetrahedral fullerene cage Si28 can be fully stabilized by encapsulating a tetrahedral metallic cluster (Al4 or Ga4). To our knowledge, this is the first predicted endohedral silicon fullerene that can retain perfectly the same cage structure (without puckering) as the carbon fullerene counterpart (Td …
Large-Scale Molecular-Dynamics Simulation Of Nanoscale Hydrophobic Interaction And Nanobubble Formation, Takahiro Koishi, Kenji Yasuoka, Toshikazu Ebisuzaki, S. Yoo, Xiao Cheng Zeng
Large-Scale Molecular-Dynamics Simulation Of Nanoscale Hydrophobic Interaction And Nanobubble Formation, Takahiro Koishi, Kenji Yasuoka, Toshikazu Ebisuzaki, S. Yoo, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We performed large-scale molecular-dynamics simulation of nanoscale hydrophobic interaction manifested by the formation of nanobubble between nanometer-sized hydrophobic clusters at constrained equilibrium. Particular attention is placed on the tendency of formation and stability of nanobubbles in between model nanoassemblies which are composed of hydrophobic clusters (or patches) embedded in a hydrophilic substrate. On the basis of physical behavior of nanobubble formation, we observed a change from short-range molecular hydrophobic interaction to midrange nanoscopic interaction when the length scale of hydrophobe approaches to about 1 nm. We investigated the behavior of nanobubble formation with several different patterns of nonpolar-site distribution on …
Coarse-Grained Free-Energy-Functional Treatment Of Quasistatic Multiscale Processes In Heterogeneous Materials, H. Zhou, Ruqiang Feng, Dennis J. Diestler, Xiao Cheng Zeng
Coarse-Grained Free-Energy-Functional Treatment Of Quasistatic Multiscale Processes In Heterogeneous Materials, H. Zhou, Ruqiang Feng, Dennis J. Diestler, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A new treatment of quasistatic (reversible) multiscale processes in heterogeneous materials at nonzero temperature is presented. The system is coarse grained by means of a finite-element mesh. The coarse-grained free-energy functional (of the positions of the nodes of the mesh) appropriate to the thermodynamic-state variables controlled in the relevant process is minimized. Tests of the new procedure on a Lennard-Jonesium crystal yield thermomechanical properties in good agreement with the “exact” atomistic results.
Structures And Stability Of Medium-Sized Silicon Clusters. Iii. Reexamination Of Motif Transition In Growth Pattern From Si15 To Si20, Soohaeng Yoo, Xiao Cheng Zeng
Structures And Stability Of Medium-Sized Silicon Clusters. Iii. Reexamination Of Motif Transition In Growth Pattern From Si15 To Si20, Soohaeng Yoo, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
It has been established from experiments that stable medium-sized ionic clusters Si15–Si20 are prolate in shape. Density-functional theories (DFTs) also predict that nearly all low-lying neutral clusters in this size range are prolate in shape. Moreover, most of them are built onto two generic structural motifs, either the tricapped-trigonal-prism (TTP) Si9 motif or the six/six Si6/Si6 (sixfold-puckered hexagonal ring Si6 plus six-atom tetragonal bipyramid Si6) motif. However, it appears that the exact location of the TTP-to-six/six motif transition is dependent on the functional (e.g., PBE or BLYP) used in the …
Melting Temperature Of Ice IH Calculated From Coexisting Solid-Liquid Phases, J. Wang, S. Yoo, Jaeil Bai, James R. Morris, Xiao Cheng Zeng
Melting Temperature Of Ice IH Calculated From Coexisting Solid-Liquid Phases, J. Wang, S. Yoo, Jaeil Bai, James R. Morris, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
The purpose of this paper is twofold: (1) to compute the melting temperature (Tm) of ice Ih with both TIP4P and TIP5P models by using the two-phase coexistence method and to compare with previously obtained Tm; (2) to compute the Tm using recently improved TIP4P and TIP5P models, namely, the TIP4P-Ew (Ref. 6) and TIP5P-Ew (Ref. 7) models. Both models are developed specifically for use with Ewald techniques. The TIP4P-Ew model, in particular, has shown substantial improvement over the original TIP4P model as it can reproduce the density maximum at about 274 K, …
Ab Initio Calculation Of Bowl, Cage, And Ring Isomers Of C20 And C20-, Wei An, Yi Gao, Satya S. Bulusu, Xiao Cheng Zeng
Ab Initio Calculation Of Bowl, Cage, And Ring Isomers Of C20 And C20-, Wei An, Yi Gao, Satya S. Bulusu, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
High-level ab initio calculations have been carried out to reexamine relative stability of bowl, cage, and ring isomers of C20 and C20-. The total electronic energies of the three isomers show different energy orderings, strongly depending on the hybrid functionals selected. It is found that among three popular hybrid density-functional (DF) methods B3LYP, B3PW91, PBE1PBE, and a new hybrid-meta-DF method TPSSKCIS, only the PBE1PBE method (with cc-pVTZ basis set) gives qualitatively correct energy ordering as that predicted from ab initio CCSD(T)/cc-pVDZ [CCSD(T)—coupled-cluster method including singles, doubles, and noniterative perturbative triples; cc-pVDZ—correlation consistent polarized valence double zeta] …
Cooperative Effects In Two-Dimensional Ring-Like Networks Of Three-Center Hydrogen Bonding Interactions, Ruben D. Parra, Satya S. Bulusu, Xiao Cheng Zeng
Cooperative Effects In Two-Dimensional Ring-Like Networks Of Three-Center Hydrogen Bonding Interactions, Ruben D. Parra, Satya S. Bulusu, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Cooperative effects in two-dimensional cyclic networks containing intermolecular three-centered hydrogen bonding interactions of the type H1&#;A&#;H2 are investigated by means of ab intio molecular orbital and density functional theory calculations. Ring-like clusters consisting of three and up to nine monomers of the cis–cis isomer of carbonic acid H2CO3 are used as basic models, where each unit acts simultaneously as a double hydrogen-bond donor and double hydrogen-bond acceptor. Cooperative effects based on binding energies are evident for (H2CO3)n, where n goes from 2 to 9. Thus, the ZPVE-corrected dissociation …
Search For Global Minimum Geometries For Medium Sized Germanium Clusters: Ge12–Ge20, Satya S. Bulusu, S. Yoo, Xiao Cheng Zeng
Search For Global Minimum Geometries For Medium Sized Germanium Clusters: Ge12–Ge20, Satya S. Bulusu, S. Yoo, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We have performed an unbiased search for the global minimum geometries of small-to-medium sized germanium clusters Gen (12≤n≤18) as well as a biased search (using seeding method) for Gen (17≤n≤20). We employed the basin-hopping algorithm coupled with the plane-wave pseudopotential density functional calculations. For each size, we started the unbiased search with using several structurally very different initial clusters, or we started the biased search with three different seeds. Irrespective of the initial structures of clusters we found that the obtained lowest-energy clusters of the size n=12–16 and 18 are the same. Among …
Planar-To-Tubular Structural Transition In Boron Clusters: B20 As The Embryo Of Single-Walled Boron Nanotubes, Boggavarapu Kiran, Satya S. Bulusu, Hua-Jin Zhai, Soohaeng Yoo, Xiao Cheng Zeng, Lai-Sheng Wang
Planar-To-Tubular Structural Transition In Boron Clusters: B20 As The Embryo Of Single-Walled Boron Nanotubes, Boggavarapu Kiran, Satya S. Bulusu, Hua-Jin Zhai, Soohaeng Yoo, Xiao Cheng Zeng, Lai-Sheng Wang
Xiao Cheng Zeng Publications
Experimental and computational simulations revealed that boron clusters, which favor planar (2D) structures up to 18 atoms, prefer 3D structures beginning at 20 atoms. Using global optimization methods, we found that the B20 neutral cluster has a double-ring tubular structure with a diameter of 5.2 Å. For the B20- anion, the tubular structure is shown to be isoenergetic to 2D structures, which were observed and confirmed by photoelectron spectroscopy. The 2D-to-3D structural transition observed at B20, reminiscent of the ring-to-fullerene transition at C20 in carbon clusters, suggests it may be considered as the embryo …