# Atomic and electronic structure of tetrahedral amorphous carbon surfaces from density functional theory: Properties and simulation strategies

Tutkimustuotos: Lehtiartikkeli

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**Atomic and electronic structure of tetrahedral amorphous carbon surfaces from density functional theory : Properties and simulation strategies.** / Caro, Miguel A.; Zoubkoff, Remi; Lopez-Acevedo, Olga; Laurila, Tomi.

Tutkimustuotos: Lehtiartikkeli

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*Carbon*, Vuosikerta. 77, Sivut 1168-1182. https://doi.org/10.1016/j.carbon.2014.06.060

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*Carbon*,

*77*, 1168-1182. https://doi.org/10.1016/j.carbon.2014.06.060

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TY - JOUR

T1 - Atomic and electronic structure of tetrahedral amorphous carbon surfaces from density functional theory

T2 - Properties and simulation strategies

AU - Caro, Miguel A.

AU - Zoubkoff, Remi

AU - Lopez-Acevedo, Olga

AU - Laurila, Tomi

PY - 2014/10

Y1 - 2014/10

N2 - We present a computational study of tetrahedral amorphous carbon surfaces within density functional theory. The samples studied contain of the order of 250-300 atoms with densities in the range 2.78-3.12 g/cm(3). Bulk samples within and below that range are also studied as reference. The morphological features are characterized by calculating local density and sp(2)/sp(3) fraction, and with a new tool based on the analysis of the topology of the 4-atom sp(2) chains found in the structures. This allows to establish that sp(2) clustering occurs predominantly with the formation of olefinic chains, with a smaller amount of aromatic-ring structures formed. This preference for olefinic chains is present both in bulk and reconstructed surfaces. The degree of localization of the electronic states is obtained with a participation ratio analysis, showing a direct relation with density and sp(2) fraction. The position of the surfaces Fermi level is calculated about 4 eV below the vacuum level, a result that appears to be almost independent of sample density. Finally, a passivation scheme is presented that allows to reduce the overall number of atoms in the surfaces without compromising the level of description of their properties, optimizing them in terms of the associated computational cost. (C) 2014 Elsevier Ltd. All rights reserved.

AB - We present a computational study of tetrahedral amorphous carbon surfaces within density functional theory. The samples studied contain of the order of 250-300 atoms with densities in the range 2.78-3.12 g/cm(3). Bulk samples within and below that range are also studied as reference. The morphological features are characterized by calculating local density and sp(2)/sp(3) fraction, and with a new tool based on the analysis of the topology of the 4-atom sp(2) chains found in the structures. This allows to establish that sp(2) clustering occurs predominantly with the formation of olefinic chains, with a smaller amount of aromatic-ring structures formed. This preference for olefinic chains is present both in bulk and reconstructed surfaces. The degree of localization of the electronic states is obtained with a participation ratio analysis, showing a direct relation with density and sp(2) fraction. The position of the surfaces Fermi level is calculated about 4 eV below the vacuum level, a result that appears to be almost independent of sample density. Finally, a passivation scheme is presented that allows to reduce the overall number of atoms in the surfaces without compromising the level of description of their properties, optimizing them in terms of the associated computational cost. (C) 2014 Elsevier Ltd. All rights reserved.

KW - ab initio

KW - amorphous carbon

KW - density functional theory

KW - simulation

KW - surfaces

KW - ab initio

KW - amorphous carbon

KW - density functional theory

KW - simulation

KW - surfaces

KW - ab initio

KW - amorphous carbon

KW - density functional theory

KW - simulation

KW - surfaces

UR - http://www.sciencedirect.com/science/article/pii/S000862231400606X#

U2 - 10.1016/j.carbon.2014.06.060

DO - 10.1016/j.carbon.2014.06.060

M3 - Article

VL - 77

SP - 1168

EP - 1182

JO - Carbon

JF - Carbon

SN - 0008-6223

ER -

ID: 779429