Wannier function analysis of tetrahedral amorphous networks

McCulloch, D. G.; Merchant, A. R.; Marks, Nigel A.; Cooper, N. C.; Fitzhenry, P; Bilek, M.M.M.; McKenzie, David R.

doi:10.1016/s0925-9635(03)00196-1

Cited by 6 publications

(5 citation statements)

References 26 publications

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“…4 ). We also conducted Wannier function analysis to examine the bonding nature in this amorphous carbon structure 29 , 30 , and derived the percentage of tetrahedral bonding to be 98% (Supplementary Fig. 5 ).…”

Section: Resultsmentioning

confidence: 99%

“…The structural differences between amorphous diamond and other amorphous carbon materials were discussed in Supplementary Note 1 . We also conducted Wannier function analysis to examine the bonding nature in this structure 29 , 30 , 41 . The center of maximally localized Wannier functions (WFC) reflects the bonding of the atoms.…”

Section: Methodsmentioning

confidence: 99%

“…The center of maximally localized Wannier functions (WFC) reflects the bonding of the atoms. Similar techniques have been used to characterize amorphous Si and C networks before 29 , 42 . We have obtained the pair distribution of all the WFCs of occupied Wannier functions (Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

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Synthesis of quenchable amorphous diamond

et al. 2017

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Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp 3-carbon network bonding. Crystallinity is another major controlling factor for materials properties. Although other Group-14 elements silicon and germanium have complementary crystalline and amorphous forms consisting of purely sp 3 bonds, purely sp 3-bonded tetrahedral amorphous carbon has not yet been obtained. In this letter, we combine high pressure and in situ laser heating techniques to convert glassy carbon into “quenchable amorphous diamond”, and recover it to ambient conditions. Our X-ray diffraction, high-resolution transmission electron microscopy and electron energy-loss spectroscopy experiments on the recovered sample and computer simulations confirm its tetrahedral amorphous structure and complete sp 3 bonding. This transparent quenchable amorphous diamond has, to our knowledge, the highest density among amorphous carbon materials, and shows incompressibility comparable to crystalline diamond.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Synthesis of quenchable amorphous diamond

et al. 2017

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“…The positions of Wannier function centers give insight into bonding charges in the system. Following previous studies ( 44 , 45 ), we define two C sites as bonded if they share a Wannier function center (X) within a given cutoff distance, chosen to correspond to the first minimum of the C–X pair correlation function of diamond.…”

Section: Resultsmentioning

confidence: 99%

Influence of nuclear quantum effects on the electronic properties of amorphous carbon

Kundu

Song

Galli

2022

Proc. Natl. Acad. Sci. U.S.A.

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We carry out quantum simulations to study the physical properties of diamond-like amorphous carbon by coupling first-principles molecular dynamics with a quantum thermostat, and we analyze multiple samples representative of different defective sites present in the disordered network. We show that quantum vibronic coupling is critical in determining the electronic properties of the system, in particular its electronic and mobility gaps, while it has a moderate influence on the structural properties. We find that despite localized electronic states near the Fermi level, the quantum nature of the nuclear motion leads to a renormalization of the electronic gap surprisingly similar to that found in crystalline diamond. We also discuss the notable influence of nuclear quantum effects on band-like and variable-hopping mechanisms contributing to electrical conduction. Our calculations indicate that methods often used to evaluate electron–phonon coupling in ordered solids are inaccurate to study the electronic and transport properties of amorphous semiconductors composed of light atoms.

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“…The Car-Parrinello Molecular Dynamics Consortium website [172] lists numerous papers that have been published on this method since 1994; however, this list is not exhaustive. To give an idea of the wide range of applications studied by this method, we list several papers in materials science [32,78,106,109,185], physics [14,20,46,143,154], chemistry [23,57,87,137,184], and biology [56,80,113,132,146] that employ this method. For information on recent advances in chemistry and materials science with Car-Parinello molecular dynamics methods, see [1].…”

Section: The "Car-parrinello" Viewpointmentioning

confidence: 99%

Numerical Methods for Electronic Structure Calculations of Materials

Saad¹,

Chelikowsky²,

Shontz³

2010

SIAM Rev.

273

166

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The goal of this article is to give an overview of numerical problems encountered when determining the electronic structure of materials and the rich variety of techniques used to solve these problems. The paper is intended for a diverse scienti£c computing audience. For this reason, we assume the reader does not have an extensive background in the related physics. Our overview focuses on the nature of the numerical problems to be solved, their origin, and on the methods used to solve the resulting linear algebra or nonlinear optimization problems. It is common knowledge that the behavior of matter at the nanoscale is, in principle, entirely determined by the Schrödinger equation. In practice, this equation in its original form is not tractable. Successful, but approximate, versions of this equation, which allow one to study nontrivial systems, took about £ve or six decades to develop. In particular, the last two decades saw a ¤urry of activity in developing effective software. One of the main practical variants of the Schrödinger equation is based on what is referred to as Density Functional Theory (DFT). The combination of DFT with pseudopotentials allows one to obtain in an ef£cient way the ground state con£guration for many materials. This article will emphasize pseudopotentialdensity functional theory, but other techniques will be discussed as well.

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Wannier function analysis of tetrahedral amorphous networks

Cited by 6 publications

References 26 publications

Synthesis of quenchable amorphous diamond

Synthesis of quenchable amorphous diamond

Influence of nuclear quantum effects on the electronic properties of amorphous carbon

Numerical Methods for Electronic Structure Calculations of Materials

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