Semi-metallic Be5C2 monolayer global minimum with quasi-planar pentacoordinate carbons and negative Poisson’s ratio

Wang, Yu; Li, Feng; Li, Yafei; Chen, Zhongfang

doi:10.1038/ncomms11488

Cited by 263 publications

(185 citation statements)

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“…Be 5 C 2 monolayer, 26 Be 2 C monolayer. 27 In a recent literature, a tug-of-war between classical and multicenter bonding is demonstrated in Be containing H-(Be) n -H species.…”

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confidence: 99%

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

Aeberhard

et al. 2018

RSC Adv.

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As one of the most prominent metal-hydrides, beryllium hydride has received much attention over the past several decades, since 1978, and is considered as an important hydrogen storage material. By reducing the dimensionality from 3 to 2, the beryllium hydride monolayer is isoelectronic with graphene; thus the existence of its two-dimensional (2D) form is theoretically feasible and experimentally expected. However, little is known about its 2D form. In this work, by a global minimum search with the particle swarm optimization method via density functional theory computations, we predicted two new stable structures for the beryllium hydride sheets, named a-BeH 2 and b-BeH 2 monolayers. Both structures have more favorable thermodynamic stability than the recently reported planar square form (Nanoscale, 2017, 9, 8740), due to the forming of multicenter delocalized Be-H bonds. Utilizing the recently developed SSAdNDP method, we revealed that three-center-two-electron (3c-2e) delocalized Be-H bonds are formed in the a-BeH 2 monolayer, while for the b-BeH 2 monolayer, novel four-center-twoelectron (4c-2e) delocalized bonds are observed in the 2D system for the first time. These unique multicenter chemical bonds endow both a-and b-BeH 2 with high structural stabilities, which are further confirmed by the absence of imaginary modes in their phonon spectra, the favorable formation energies comparable to bulk and cluster beryllium hydride, and the high mechanical strength. These results indicate the potential for experimental synthesis. Furthermore, both a-and b-BeH 2 are widebandgap semiconductors, in which the a-BeH 2 has unusual mechanical properties with a negative Poisson's ratio of À0.19. If synthesized, it would attract interest both in experiment and theory, and be a new member of the 2D family isoelectronic with graphene.

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“…Be 5 C 2 monolayer, 26 Be 2 C monolayer. 27 In a recent literature, a tug-of-war between classical and multicenter bonding is demonstrated in Be containing H-(Be) n -H species.…”

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confidence: 99%

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

Aeberhard

et al. 2018

RSC Adv.

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“…We chose metal Be for 2D Be-N sheet due to its flexible bonding ability as seen in Be 2 C, 22 Be 5 C 2 , 23 and h-BeS 24 sheets, moreover, Be and N have close covalent radius ( 0.9 Å for Be vs 0.75 Å for N). We followed the strategy of "atomic transmutation", 25 which means substituting certain type of elements with its neighboring elements in the periodic table for enhanced or newly induced properties.…”

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confidence: 99%

A Honeycomb BeN₂ Sheet with a Desirable Direct Band Gap and High Carrier Mobility

Zhang

Sun

2016

J. Phys. Chem. Lett.

101

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Based on ab initio evolutionary crystal structure search computation, we report a new phase of phosphorus called green phosphorus (λ-P), which exhibits the direct band gaps ranging from 0.7 to 2.4 eV and the strong anisotropy in optical and transport properties. Free energy calculations show that a single-layer form, termed green phosphorene, is energetically more stable than blue phosphorene and a phase transition from black to green phosphorene can occur at temperatures above 87 K. Due to its buckled structure, green phosphorene can be synthesized on corrugated metal surfaces rather than clean surfaces. The successful isolation of graphene [1], a single layer of carbon atoms in a two-dimensional (2D) honeycomb lattice, has generated tremendous interest in 2D layered materials [2]. Various applications using graphene have been explored based on the unusual properties such as massless Dirac fermions, high mobility, and high thermal conductivity [3, 4]. However, the gapless nature of graphene has been an obstacle in practical applications for electronic devices due to its low on/off ratios [5]. Transition metal dichalcogenides belonging to the family of 2D materials have the semiconducting gaps in the visible range, but the carrier mobility in thin films is significanlty reduced [6]. Recently, atomically thin black phosphorus has been successfully separated from its lay-ered bulk [7, 8], and this emerging 2D material with the tunable band gap by varying the number of atomic layers bridges the gap between graphene and transition metal dichalcogenides [9, 10]. Due to its high anisotropic mobility , black phosphorus is considered as a promising material for electronic and optoelectronic devices [6-8, 11, 12]. Elemental phosphorus is known to exist in several three-dimensional (3D) allotropes, such as red, white, and violet phosphorus, besides black phosphorus (α-P) which is the most stable phase among them. Due to the presence of various phases, it is expected that an unknown phosphorus allotrope will form under the control of substrate, temperature, and pressure. Zhu and Tománek proposed a new stable phase of phosphorus called blue phosphorus (β-P), with the structural similarity to a buckled graphene [13]. Unlike black phosphorus, blue phosphorus displays the indirect band gaps, regardless of the number of atomic layers. Other 2D structures such as γ-, δ-, ε-, ζ-, η-, θ-, and ψ-phosphorene were later suggested based on theoretical calculations [14-18]. Recently, blue phosphorene has been successfully synthesized on the Au(111) substrate by molecular beam epi-taxy [19]. The realization of blue phosphorene not only opens up the potential of various metastable allotropes but also motivates research into a new level of phosphorus that provides exciting characteristics such as broad band gaps and high anisotropic mobility. In this work, we use an ab initio evolutionary crystal structure search method to explore a new phosphorus allotrope called green phosphorus. The new P allotrope belongs to a class of 2D materials an...

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“…The electronic properties show that Be 2 C has a direct gap of about 1.52 eV, which is suitable for electronic and optoelectronic applications in the future. Later, Wang et al found the lowest energy structure of 2D Be 5 C 2 with the same method . For Be 5 C 2 monolayer, each carbon atom binds with five beryllium atoms in almost the same plane, forming a quasi‐planar pentacoordinate carbon (ppC) moiety.…”

Section: Applicationsmentioning

confidence: 99%

“…Later, Wang et al found the lowest energy structure of 2D Be 5 C 2 with the same method. 105 For Be 5 C 2 monolayer, each carbon atom binds with five beryllium atoms in almost the same plane, forming a quasi-planar pentacoordinate carbon (ppC) moiety. It is semimetallic with a Dirac-like point and also has an unusual negative Poisson's ratio, which is expected to have wide applications in electronics and mechanics.…”

Section: C-be Alloymentioning

confidence: 99%

Prediction of two‐dimensional materials by the global optimization approach

Luo

Xiang

2016

WIREs Comput Mol Sci

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Crystal structure prediction is one of the most fundamental challenges in the physics and chemistry sciences. In recent years, this problem has gained much practical success by the global optimization approach. Here, we survey some recent progress in finding the global minimum of two‐dimensional (2D) materials, and introduce some details of these global optimization approach. Then, we will give some typical examples to demonstrate their advantages for 2D crystal structure prediction. Finally, the future directions and challenges are briefly discussed. WIREs Comput Mol Sci 2017, 7:e1295. doi: 10.1002/wcms.1295 This article is categorized under: Structure and Mechanism > Computational Materials Science Electronic Structure Theory > Density Functional Theory

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Semi-metallic Be5C2 monolayer global minimum with quasi-planar pentacoordinate carbons and negative Poisson’s ratio

Cited by 263 publications

References 69 publications

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

A Honeycomb BeN₂ Sheet with a Desirable Direct Band Gap and High Carrier Mobility

Prediction of two‐dimensional materials by the global optimization approach

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Semi-metallic Be5C2 monolayer global minimum with quasi-planar pentacoordinate carbons and negative Poisson’s ratio

Cited by 263 publications

References 69 publications

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

Global minimum beryllium hydride sheet with novel negative Poisson's ratio: first-principles calculations

A Honeycomb BeN2 Sheet with a Desirable Direct Band Gap and High Carrier Mobility

Prediction of two‐dimensional materials by the global optimization approach

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A Honeycomb BeN₂ Sheet with a Desirable Direct Band Gap and High Carrier Mobility