Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session L23: Computational Materials Discovery and Design - Graphene and 2D MaterialsFocus
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Sponsoring Units: DMP DCOMP Chair: Mahesh Neupane, Army Research Lab Room: 322 |
Wednesday, March 16, 2016 11:15AM - 11:51AM |
L23.00001: Computational design and optimization of energy materials Invited Speaker: Maria Chan The use of density functional theory (DFT) to understand and improve energy materials for diverse applications -- including energy storage, thermal management, catalysis, and photovoltaics -- is widespread. The further step of using high throughput DFT calculations to design materials and has led to an acceleration in materials discovery and development. Due to various limitations in DFT, including accuracy and computational cost, however, it is important to leverage effective models and, in some cases, experimental information to aid the design process. In this talk, I will discuss efforts in design and optimization of energy materials using a combination of effective models, DFT, machine learning, and experimental information. [Preview Abstract] |
Wednesday, March 16, 2016 11:51AM - 12:03PM |
L23.00002: High-throughput prediction of novel two-dimensional materials Nicolas Mounet, Philippe Schwaller, Andrea Cepellotti, Andrius Merkys, Ivano Eligio Castelli, Marco Gibertini, Giovanni Pizzi, Nicola Marzari As a crucial step towards the identification of novel and promising 2D materials, we provide here a large scale first-principles exploration and characterization of such compounds. More than 300,000 three-dimensional structures from several crystallographic databases are screened systematically by checking the absence of chemical bonds between adjacent layers, identifying close to 5,000 layered systems. Then DFT calculations of the van der Waals interlayer bonding are performed with automatic workflows, while systematically assessing the metallic, insulating or magnetic character of the materials obtained. Following full atomic and cell relaxations, phonon dispersions are computed as a first step towards the assessment of thermodynamic properties. Thanks to the AiiDA materials' informatics platform [1], and in particular its automatic workflow engine, database structure, sharing capabilities, and pipelines to/from crystallographic repositories, the systematic and reproducible calculation of these properties becomes straightforward, together with seamless accessibility and sharing. [1] G. Pizzi, A. Cepellotti, R. Sabatini, N. Marzari and B. Kozinsky, Comp. Mat. Sci. 111, 218 (2016). [Preview Abstract] |
Wednesday, March 16, 2016 12:03PM - 12:15PM |
L23.00003: New Monolayered Materials Exhibiting Unusual Electronic Properties Alejandro Lopez-Bezanilla, Ivar Martin, Peter B. Littlewood Computationally based approaches are allowing to progress in the discovery and design of nano-scaled materials. Here we propose a series of new mono-layered compounds with exotic properties. By means of density functional theory calculations we demonstrate that the pentagonal arrangement of SiC2 yields an inverted distribution of the p-bands which leads to an unusual electronic behaviour of the material under strain [J. Phys. Chem. C, 2015, 119 (33), pp 19469]. A different pentagonal arrangement of C atoms enables the formation of Dirac cones which, unlike graphene, exhibit a strain-mediated tunable band gap. [Preview Abstract] |
Wednesday, March 16, 2016 12:15PM - 12:27PM |
L23.00004: First-principles Study of Size and Edge Dependent Properties of MXene Nanoribbons Liang Hong, Robert Klie, Serdar Ogut One-dimensional nanoribbons can be created with considerably different physical properties from their two-dimensional (2D) counterparts due to quantum confinement and surface effects. MXenes are a new class of 2D materials with many potential applications and have drawn significant attention. We perform first-principles calculations to explore the size and edge dependent properties of a wide range of MXene nanoribbons cut from 2D semiconducting MXenes. Our results suggest that semiconducting versus metallic nature as well as the size of the band gap for semiconducting MXene nanoribbons can be tuned as a function of size, chemical composition, and functional groups, which can be useful for future designs of MXene nanostructures with interesting electronic and optical properties. [Preview Abstract] |
Wednesday, March 16, 2016 12:27PM - 12:39PM |
L23.00005: First-principles study of 2D electride : Gadolinium carbide Chandani Nandadasa, Seong-Gon Kim, Sungho Kim, Sung Wng Kim Electrides are an exclusive class of ionic compounds in which some electrons are occupying crystal voids instead of attaching to specific atoms or bonds. Using first-principles density functional theory calculations, we study structural, electronic and magnetic properties of Gd$_{2}$C. The theoretically predicted structure of Gd$_{2}$C is in good agreement with the available experimental data. Energy band diagram of Gd$_{2}$C shows that they are crossing the Fermi level. Projected electronic density of states plots indicate that the interstitial sites are the main contributor to the density of states at the Fermi level. Charge of individual atoms including interstitial site are obtained using Bader analysis. Magnetic properties of Gd$_{2}$C is determined from magnetization density plots. Work functions of Gd$_{2}$C are determined for (001) and (100) surfaces with the technique of macroscopic average of electrostatic potential with the Fermi energy of bulk. [Preview Abstract] |
Wednesday, March 16, 2016 12:39PM - 12:51PM |
L23.00006: \textbf{Phase Transition between Black and Blue Phosphorenes: A Quantum Monte Carlo Study} Lesheng Li, Yi Yao, Kyle Reeves, Yosuke Kanai Phase transition of the more common black phosphorene to blue phosphorene is of great interest because they are predicted to exhibit unique electronic and optical properties[1]. However, these two phases are predicted to be separated by a rather large energy barrier. In this work, we study the transition pathway between black and blue phosphorenes by using the variable cell nudge elastic band method combined with density functional theory calculation. We show how diffusion quantum Monte Carlo method can be used for determining the energetics of the phase transition and demonstrate the use of two approaches for removing finite-size errors. Finally, we predict how applied stress can be used to control the energetic balance between these two different phases of phosphorene. [1] Zhu, Zhen, and David Tom\'{a}nek. "Semiconducting layered blue phosphorus: A computational study."~\textit{Physical review letters}~112.17 (2014): 176802. [Preview Abstract] |
Wednesday, March 16, 2016 12:51PM - 1:03PM |
L23.00007: Induced Magnetization and Band Gap in Graphene-Like Materials: Towards Spintronics Xuan Luo, Jesse Cai We use first principles calculations incorporated within the ABINIT package to$\backslash $pardanalyze the potential of two dimensional graphene-like materials in spintronics. Spintronics haspotential to vastly improve upon and decrease the size of existing silicon based technology.use four transition metals, Mn, Fe, Co, and Ni, to dope six graphene-like materials: graphene, boron nitride, silicene, molybdenum disulfide, molybdenum diselenide and black phosphorene. With the addition of a transition metal dopant, boron nitride, silicene, molybdenum disulfide, molybdenum diselenide and black phosphorene all displayed magnetization and a band gap in at least one configuration. Doped graphene, however,showed magnetization but no band gap. By using a hybrid graphene/boron nitride surface, or by placing graphene on top of boron nitride, magnetization and a band gap was observed. By altering the surface and the metal dopant, we have the ability to tune the band gap and magnetization. In conclusion, we find that all six graphene-like materials show promise in developing spintronics. [Preview Abstract] |
Wednesday, March 16, 2016 1:03PM - 1:15PM |
L23.00008: Anisotropic Dirac Fermions in Novel 2D Carbon and Silicon Allotropes Zhenhai Wang, Mingwen Zhao, Xiang-Feng Zhou, Qiang Zhu, Xiaoming Zhang, Huafeng Dong, Artem R. Oganov, Shumin He, Peter Gr\"{u}nberg Graphene, due to its unique Dirac cones with linear dispersion, exhibits a number of novel physics, such as high carrier mobility and quantum hall effect. Successful preparation of graphene in 2004 has inspired further searches for other 2D Dirac materials. Using systematic evolutionary structure searching, here we proposed one interesting type of 2D Dirac allotropes, which were named as `phagraphene' [Nano. Lett. 15, 6182 (2015)] and `siliconeet' respectively. Compared with the isotropic energy dispersion in graphene, the Dirac cones in these samples are direction-dependent. Further investigations proved that such anisotropic behaviors and the distorted Dirac cones are robust against external strain with tunable Fermi velocities. These predictions pave a new way to construct novel functional Dirac materials that might have potential applications in future. [Preview Abstract] |
Wednesday, March 16, 2016 1:15PM - 1:27PM |
L23.00009: Carbon Phosphide Monolayers: Novel 2D Materials Gaoxue Wang, Ravindra Pandey, Shashi P. Karna Monolayers of carbon phosphide are investigated using the particle swarm optimization and first-principles methods. The calculated results for $\alpha $-, $\beta $-, and $\gamma $- phases of carbon phosphide show novel properties including the presence of Dirac cones in the band structure. These configurations are composed of sp$^{\mathrm{2}}$ hybridized C atoms and sp$^{\mathrm{3}}$ hybridized P atoms in a hexagonal network with three-fold coordinated atoms. $\alpha $- and $\beta $- phases are semiconducting with highly anisotropic electronic and mechanical properties whereas $\gamma $-CP is semi-metallic with a high electron mobility. Our results suggest that the group IV-V binary monolayers can be considered as a new family of 2D materials for electronics and optoelectronics applications at nanoscale. [Preview Abstract] |
Wednesday, March 16, 2016 1:27PM - 1:39PM |
L23.00010: Influence of Metal Substrates on the Nucleation of Chemical Vapor Deposition Growth of Graphene Jia Li, Lixiang Zhong, Yuanchang Li Using \textit{ab initio} calculations, we systematically investigate the graphene nucleation on ten kinds of metal substrates that have been reported for the chemical vapor deposition growth of graphene. Noble metals (Cu, Ag and Au) and Co have a kinetic smallest graphene precursor, corresponding to the structural transition from linear chain to $sp^2$ compact cluster. Ru, Rh, Ir and Pt have a energetic smallest graphene precursor, which is much larger than that in terms of kinetics. While for Ni and Pd, the carbon atoms trend to immerse inside the metals, resulting in the distinctively different growth mechanism from other metals. The different influence of metals is associated with their characterized carbon-metal and carbon-carbon coupling competition. The incorporation of five-membered rings into the $sp^2$ compact cluster is the result of the competition between the curvature energy and the edge formation energy of graphene islands, and is suitable for the enlargement of graphene domain. And the effect of experimental conditions such as temperature, step or defects on the nucleation of graphene at different metal substrates is also discussed. [Preview Abstract] |
Wednesday, March 16, 2016 1:39PM - 1:51PM |
L23.00011: Stability and Superconductivity of N-(B-) Doped Graphene Jian Zhou, Qiang Sun, Qian Wang, Puru Jena Superconductivity of two-dimensional honeycomb lattice has been predicted to possess a wealth of fascinating properties. For example, if graphene is heavily electron/hole doped, it exhibits high-temperature topological superconductivity. However, to achieve this, the carrier concentration will be too high, and graphene will be dynamically unstable. One possible route will be atomic substitution by B or N atoms, which, unfortunately, again is dynamic instability in nature. Using density functional theory combined with a global structural search and phonon dispersion calculations, we show that an ordered 50{\%} N- (B-) doped graphene can be made energetically and dynamically stable by simultaneous doping carriers and applying biaxial tensile strain. By using a simple model, we show that tensile strain reduces the electrostatic interaction and moves imaginary phonon dispersion to be positive. Electron-phonon coupling calculations show that the N- (B-) doped graphene is superconducting with critical temperature reaching 66 K in the case of 50{\%} N-doped graphene. [Preview Abstract] |
Wednesday, March 16, 2016 1:51PM - 2:03PM |
L23.00012: Next Generation Monolayer Structures of Group V Elements: Nitrogene and Antimonene Ongun Ozcelik, Olcay Akturk, Engin Durgun, Salim Ciraci Based on first-principles density functional theory, we predict that nitrogen and antimony atoms can form single-layer, buckled honeycomb structures called nitrogene[1] and antimonene[2], which are rigid and stable even above room temperature. The 2D crystalline phase of nitrogen, which corresponds to a local minimum in the Born-Oppenheimer surface, is a nonmagnetic insulator with saturated pi bonds. When grown on a substrate like Al(111) surface or graphene, nitrogene binds weakly to substrates and hence preserves its free-standing properties, but it can easily be pealed off. Zigzag and armchair nanoribbons have fundamental band gaps derived from reconstructed edge states. These band gaps are tunable with size and suitable for the emerging field of 2D electronics. Nitrogene and antimonene form not only bilayer, but also 3D graphitic multilayer structures. Single-layer nitrogene can nucleate and grow on the armchair edges of hexagonal boron nitride. Starting from the pseudo-layered character of 3D bulk crystals of antimony, we also demonstrate the formation of monolayer antimonene structure which is similar to nitrogene. [1] Phys. Rev. B 92, 125420, 2015. [2] Phys. Rev. B 91, 235446, 2015. [Preview Abstract] |
Wednesday, March 16, 2016 2:03PM - 2:15PM |
L23.00013: Design of low work function materials using alkali metal-doped transition metal dichalcogenides Sol Kim, Man Young Lee, Seong Lee, Seung-Hoon Jhi Engineering the work function is a key issue in surface science. Particularly, discovering the materials that have work functions less than 1eV is essential for efficient thermionic energy conversion. The lowest work function of materials, reported so far, is in a range of about 1eV. To design low work function materials, we chose MX$_{\mathrm{2}}$ (M$=$Mo and W; X$=$S, Se and Te) as substrates and alkali metals (Li, Na, K, Rb and Cs) as dopants, and studied their electronic structures, charge transfer, induced surface dipole moment, and work function using first-principles calculations. We found that the charge transfer from alkali metals to MX$_{\mathrm{2}}$ substrates decreases as the atomic radius of alkali metals increases. Regardless of the amount of the charge transfer, K on WTe$_{\mathrm{2}}$ exhibits the biggest surface dipole moment, which consequently makes the surface work function the lowest. Also, we found a correlation between the binding distance and the work function. [Preview Abstract] |
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