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Full-Text Articles in Physical Sciences and Mathematics
Multiwalled Ice Helixes And Ice Nanotubes, Jaeil Bai, Jun Wang, Xiao Cheng Zeng
Multiwalled Ice Helixes And Ice Nanotubes, Jaeil Bai, Jun Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We report six phases of high-density nano-ice predicted to form within carbon nanotubes (CNTs) at high pressure. High-density nano-ice self-assembled within smaller-diameter CNT (17,0) exhibits a double-walled helical structure where the outer wall consists of four double- stranded helixes, which resemble a DNA double helix, and the inner wall is a quadruple-stranded helix. Four other double-walled nano-ices, self-assembled respectively in two larger-diameter CNTs (20,0 and 22,0), display tubular structure. Within CNT (24,0), the confined water can freeze spontaneously into a triple-walled helical nanoice where the outer wall is an 18-stranded helix and the middle and inner walls are hextuple-stranded helixes.
Homogeneous Nucleation At High Supersaturation And Heterogeneous Nucleation On Microscopic Wettable Particles: A Hybrid Thermodynamic/Density-Functional Theory, T. V. Bykov, Xiao Cheng Zeng
Homogeneous Nucleation At High Supersaturation And Heterogeneous Nucleation On Microscopic Wettable Particles: A Hybrid Thermodynamic/Density-Functional Theory, T. V. Bykov, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Homogeneous nucleation at high supersaturation of vapor and heterogeneous nucleation on microscopic wettable particles are studied on the basis of Lennard-Jones model system. A hybrid classical thermodynamics and density-functional theory (DFT) approach is undertaken to treat the nucleation problems. Local-density approximation and weighted-density approximation are employed within the framework of DFT. Special attention is given to the disjoining pressure of small liquid droplets, which is dependent on the thickness of wetting film and radius of the wettable particle. Different contributions to the disjoining pressure are examined using both analytical estimations and numerical DFT calculation. It is shown that van der …
Structures And Relative Stability Of Neutral Gold Clusters: AuN (N=15–19), Satya S. Bulusu, Xiao Cheng Zeng
Structures And Relative Stability Of Neutral Gold Clusters: AuN (N=15–19), Satya S. Bulusu, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We performed a global-minimum search for low-lying neutral clusters (Aun) in the size range of n=15–19 by means of basin-hopping method coupled with density functional theory calculation. Leading candidates for the lowest-energy clusters are identified, including four for Au15, two for Au16, three for Au17, five for Au18, and one for Au19. For Au15 and Au16 we find that the shell-like flat-cage structures dominate the population of low-lying clusters, while for Au17 and Au18 spherical-like hollow-cage structures dominate the low-lying population. The transition …
Hybrid Atomistic-Coarse-Grained Treatment Of Multiscale Processes In Heterogeneous Materials: A Self-Consistent-Field Approach, Dennis J. Diestler, H. Zhou, Ruqiang Feng, Xiao Cheng Zeng
Hybrid Atomistic-Coarse-Grained Treatment Of Multiscale Processes In Heterogeneous Materials: A Self-Consistent-Field Approach, Dennis J. Diestler, H. Zhou, Ruqiang Feng, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A treatment of multiscale quasistatic processes that combines an atomistic description of microscopic heterogeneous (“near”) regions of a material with a coarse-grained (quasicontinuum) description of macroscopic homogeneous (“far”) regions is presented. The hybrid description yields a reduced system consisting of the original atoms of the near regions plus pseudoatoms (nodes of the coarse-graining mesh) of the far regions, which interact through an effective many-body potential energy Veff that depends on the thermodynamic state. The approximate nature of Veff gives rise to “ghost forces,” which are reflected in spurious heterogeneities close to interfaces between near and far regions. The …
Shape-Persistent Macrocyclic Aromatic Tetrasulfonamides: Molecules With Nanosized Cavities And Their Nanotubular Assemblies In Solid State, Lan He, Yu An, Lihua Yuan, Wen Feng, Minfeng Li, Dechun Zhang, Kazuhiro Yamato, Chong Zheng, Xiao Cheng Zeng, Bing Gong
Shape-Persistent Macrocyclic Aromatic Tetrasulfonamides: Molecules With Nanosized Cavities And Their Nanotubular Assemblies In Solid State, Lan He, Yu An, Lihua Yuan, Wen Feng, Minfeng Li, Dechun Zhang, Kazuhiro Yamato, Chong Zheng, Xiao Cheng Zeng, Bing Gong
Xiao Cheng Zeng Publications
Alkoxy side-chain-flanked diarylsulfonamide serves as a reliable structural motif for constructing macrocyclic aromatic tetrasulfonamides. This 90° structural motif is persistent both in solution and in the solid state, which allows the one-step formation of tetrasulfonamide macrocycles. These macrocycles adopt a cone-shaped conformation in solution and in the solid state. For each molecule, an interior cavity surrounded by the aromatic residues is formed. The cavity sizes of the macrocycles can be tuned by incorporating aromatic residues of proper sizes. Guest (solvent) molecules are found in the cavities and bound by side chains. In solution, 1H NMR shows that the cone …
Structural And Electronic Properties Of Gd@C60: All-Electron Relativistic Total-Energy Study, Jing Lu, Wai-Ning Mei, Yi Gao, Xiao Cheng Zeng, Mingwei Jing, Guangping Li, Renat F. Sabirianov, Zhengxiang Gao, Liping You, Jun Xu, Dapeng Yu, Hengqiang Ye
Structural And Electronic Properties Of Gd@C60: All-Electron Relativistic Total-Energy Study, Jing Lu, Wai-Ning Mei, Yi Gao, Xiao Cheng Zeng, Mingwei Jing, Guangping Li, Renat F. Sabirianov, Zhengxiang Gao, Liping You, Jun Xu, Dapeng Yu, Hengqiang Ye
Xiao Cheng Zeng Publications
Water soluble Gd-based metallofullerenes have potential application as magnetic resonance imaging contrast agent due to its higher proton relaxivities and lower toxicity. In this letter, we have investigated the structural and electronic properties of Gd@ C60, which is the most abundantly produced Gd-based metallofullerene in carbon arc process, by using all-electron relativistic density functional theory. It is found that the Gd3+ ion is bonded to a hexagonal ring of C60 by electrostatic interaction. The total spin multiplicity of Gd@C60 is S = 7. The Gd atomic orbitals are hybridized with the C60 molecular orbitals.
Adsorption Of Transition-Metal Atoms On Boron Nitride Nanotube: A Density-Functional Study, Xiaojun Wu, Xiao Cheng Zeng
Adsorption Of Transition-Metal Atoms On Boron Nitride Nanotube: A Density-Functional Study, Xiaojun Wu, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Adsorption of transition atoms on a (8,0) zigzag single-walled boron nitride (BN) nanotube has been investigated using density-functional theory methods. Main focuses have been placed on configurations corresponding to the located minima of the adsorbates, the corresponding binding energies, and the modified electronic properties of the BN nanotubes due to the adsorbates.We have systemically studied a series of metal adsorbates including all 3d transition-metal elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) and two group-VIIIA transition-metal elements (Pd and Pt). We found that many transition-metal atoms can be chemically adsorbed on the outer surface of the …
Adsorption Of Hydrogen Molecules On The Platinum-Doped Boron Nitride Nanotubes, Xiaojun Wu, J.L. Yang, Xiao Cheng Zeng
Adsorption Of Hydrogen Molecules On The Platinum-Doped Boron Nitride Nanotubes, Xiaojun Wu, J.L. Yang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Adsorption of hydrogen molecules on platinum-doped single-walled zigzag (8,0) boron nitride (BN) nanotube is investigated using the density-functional theory. The Pt atom tends to occupy the axial bridge site of the BN tube with the highest binding energy of −0.91 eV. Upon Pt doping, several occupied and unoccupied impurity states are induced, which reduces the band gap of the pristine BN nanotube. Upon hydrogen adsorption on Pt-doped BN nanotube, the first hydrogen molecule can be chemically adsorbed on the Pt-doped BN nanotube without crossing any energy barrier, whereas the second hydrogen molecule has to overcome a small energy barrier of …
Molecular Simulations Of Solid-Liquid Interfacial Tension Of Silicon, Yuk Wai Tang, Jun Wang, Xiao Cheng Zeng
Molecular Simulations Of Solid-Liquid Interfacial Tension Of Silicon, Yuk Wai Tang, Jun Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Silicon is an important semiconductor for manufacturing of microelectronic chips used in computers and other electronic devices. During the manufacturing process, liquid silicon is being solidified to make high-grade solid semiconductors. Thus, improved data of the solid-liquid interfacial properties of silicon will be useful towards optimizing the experiment condition for making better quality electronics. Yet it is difficult to perform experiments of liquid silicon due to its high melting point. Thus far, most experimental measurements of the solid-liquid interfacial tension are based on the measurement of rate of homogeneous crystal nucleation at a given undercooling. The first measurement of solidliquid …
Evidence Of Hollow Golden Cages, Satya S. Bulusu, Xi Li, Lai-Sheng Wang, Xiao Cheng Zeng
Evidence Of Hollow Golden Cages, Satya S. Bulusu, Xi Li, Lai-Sheng Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
The fullerenes are the first “free-standing” elemental hollow cages identified by spectroscopy experiments and synthesized in the bulk. Here, we report experimental and theoretical evidence of hollow cages consisting of pure metal atoms, Au–n (n = 16–18); to our knowledge, free-standing metal hollow cages have not been previously detected in the laboratory. These hollow golden cages (“bucky gold”) have an average diameter >5.5 Å, which can easily accommodate one guest atom inside.
Evidence Of Hollow Golden Cages: Supplementary Materials And Supporting Information, Satya S. Bulusu, Xi Li, Lai-Sheng Wang, Xiao Cheng Zeng
Evidence Of Hollow Golden Cages: Supplementary Materials And Supporting Information, Satya S. Bulusu, Xi Li, Lai-Sheng Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Figures 3A-3D: Simulated anion photoelectron spectra [based on the density-functional theory (DFT) calculation with the PBEPBE/LANL2DZ functional and basis set] for all of the candidate lowest-energy isomers of
Au¯15 (A),
Au¯16 (B),
Au¯17 (C), and
Au¯18 (D) identified in Fig. 3 A–D, respectively.
Figures 4A-4E: Top-10 lowest-energy isomers of Au¯15, Au¯16, Au¯17, Au¯18, and Au¯19 obtained from a basin-hopping global search combined with DFT optimization and total-energy calculation.
Table 2: The experimental adiabatic detachment energies (ADEs) for Au¯n (n = 15–19) measured from the threshold …
Search For Global-Minimum Geometries Of Medium-Sized Germanium Clusters. Ii. Motif-Based Low-Lying Clusters Ge21–Ge29, S. Yoo, Xiao Cheng Zeng
Search For Global-Minimum Geometries Of Medium-Sized Germanium Clusters. Ii. Motif-Based Low-Lying Clusters Ge21–Ge29, S. Yoo, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We performed a constrained search for the geometries of low-lying neutral germanium clusters GeN in the size range of 21≤N≤29. The basin-hopping global optimization method is employed for the search. The potential-energy surface is computed based on the plane-wave pseudopotential density functional theory. A new series of low-lying clusters is found on the basis of several generic structural motifs identified previously for silicon clusters [S. Yoo and X. C. Zeng, J. Chem. Phys. 124, 054304 (2006)] as well as for smaller-sized germanium clusters [S. Bulusu et al., J. Chem. Phys. 122, 164305 (2005)]. Among the generic motifs examined, …
Structures And Relative Stability Of Medium-Sized Silicon Clusters. V. Low-Lying Endohedral Fullerenelike Clusters Si31–Si40 And Si45, Soohaeng Yoo, N. Shao, C. Koehler, T. Fraunhaum, Xiao Cheng Zeng
Structures And Relative Stability Of Medium-Sized Silicon Clusters. V. Low-Lying Endohedral Fullerenelike Clusters Si31–Si40 And Si45, Soohaeng Yoo, N. Shao, C. Koehler, T. Fraunhaum, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We have performed unconstrained search for low-lying structures of medium-sized silicon clusters Si31–Si40 and Si45, by means of the minimum-hopping global optimization method coupled with a density-functional based tight-binding model of silicon. Subsequent geometric optimization by using density-functional theory with the PBE, BLYP, and B3LYP functionals was carried out to determine the relative stability of various candidate low-lying silicon clusters obtained from the unconstrained search. The low-lying characteristics of these clusters can be affirmed by comparing the binding energies per atom of these clusters with previously determined lowest-energy clusters (Sin) in the size …
Relative Stability Of Planar Versus Double-Ring Tubular Isomers Of Neutral And Anionic Boron Cluster B20 And B20-, Wei An, Satya S. Bulusu, Yi Gao, Xiao Cheng Zeng
Relative Stability Of Planar Versus Double-Ring Tubular Isomers Of Neutral And Anionic Boron Cluster B20 And B20-, Wei An, Satya S. Bulusu, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
High-level ab initio molecular-orbital methods have been employed to determine the relative stability among four neutral and anionic B20 isomers, particularly the double-ring tubular isomer versus three low-lying planar isomers. Calculations with the fourth-order Møller-Plessset perturbation theory [MP4(SDQ)] and Dunning’s correlation consistent polarized valence triple zeta basis set as well as with the coupled-cluster method including single, double, and noniteratively perturbative triple excitations and the 6-311G(d) basis set show that the double-ring tubular isomer is appreciably lower in energy than the three planar isomers and is thus likely the global minimum of neutral B20 cluster. In contrast, calculations …
Structures And Relative Stability Of Medium-Sized Silicon Clusters. Iv. Motif Based Low-Lying Clusters Si21–Si30, Soohaeng Yoo, Xiao Cheng Zeng
Structures And Relative Stability Of Medium-Sized Silicon Clusters. Iv. Motif Based Low-Lying Clusters Si21–Si30, Soohaeng Yoo, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Structures and relative stability of four families of low-lying silicon clusters in the size range of Sin(n=21–30) are studied, wherein two families of the clusters show prolate structures while the third one shows near-spherical structures. The prolate clusters in the first family can be assembled by connecting two small-sized magic clusters Sin(n=6, 7, 9, or 10) via a fused-puckered-hexagonal-ring Si9 unit (a fragment of bulk diamond silicon), while those in the second family can be constructed on the basis of a structural motif consisting of a puckered-hexagonal-ring Si6 unit (also …