External Chemical Reactivity of Fullerenes and Nanotubes

2001 ◽  
Vol 675 ◽  
Author(s):  
Seongjun Park ◽  
Deepak Srivastava ◽  
Kyeongjae Cho
Keyword(s):  
Density Functional ◽  
Chemical Reactivity ◽  
Density Functional Theory Calculations ◽  
Reaction Energy ◽  
Potential Density ◽  
Functional Theory ◽  
Ab Initio Simulation ◽  
Total Reaction ◽  
Local Bonding ◽  
Pseudo Potential

ABSTRACTThe external chemical reactivity of graphene sheet, fullerenes and carbon nanotubes has been investigated. The total reaction energy is analyzed with several contributing terms and formulated as a function of the pyramidal angles of C atoms. We have determined the parameters for the formulae from ab initio simulation of graphene. We have applied them to predict hydrogenation energy of several nanotubes and C60, and demonstrated that the predicted total reaction energies are very close to the results of total energy pseudo-potential density functional theory calculations. This analysis can be used to predict the reaction energy and local bonding configuration of a reactant with diverse fullerenes and nanotubes within 0.1 eV accuracy.

Structural, Thermodynamic, Elastic, and Electronic Properties of α-SnS at High Pressure from First-Principles Investigations

2015 ◽  
Vol 70 (11) ◽  
pp. 949-960 ◽  
Author(s):  
Chun Mei Liu ◽  
Chao Xu ◽  
Man Yi Duan
Keyword(s):  
Experimental Data ◽  
Electronic Properties ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Energy Relation ◽  
Potential Density ◽  
Functional Theory ◽  
Free Energy Relation ◽  
Similar Growth ◽  
Pseudo Potential

AbstractSnS has potential technical applications, but many of its properties are still not well studied. In this work, the structural, thermodynamic, elastic, and electronic properties of α-SnS have been investigated by the plane wave pseudo-potential density functional theory with the framework of generalised gradient approximation. The calculated pressure-dependent lattice parameters agree well with the available experimental data. Our thermodynamic properties of α-SnS, including heat capacity CP , entropy S, and Gibbs free energy relation of –(GT –H0) curves, show similar growth trends as the experimental data. At T=298.15 K, our CP =52.31 J/mol·K, S=78.93 J/mol·K, and –(GT –H0)=12.03 J/mol all agree very well with experimental data CP =48.77 J/mol·K and 49.25 J/mol·K, S=76.78 J/mol·K, and –(GT –H0)=12.38 J/mol. The elastic constants, together with other elastic properties, are also computed. The anisotropy analyses indicate obvious elastic anisotropy for α-SnS along different symmetry planes and axes. Moreover, calculations demonstrate that α-SnS is an indirect gap semiconductor, and it transforms to semimetal with pressure increasing up to 10.2 GPa. Combined with the density of states, the characters of the band structure have been analysed in detail.

Electrical Properties of Single-Walled Carbon Nanotubes due to Compressive Load

2016 ◽  
Vol 675-676 ◽  
pp. 109-112
Author(s):  
Irfan Dwi Aditya ◽  
Sasfan Arman Wella ◽  
Widayani ◽  
Suprijadi
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Compressive Load ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Ab Initio Simulation ◽  
Walled Carbon Nanotubes ◽  
Optimized Geometries

In this paper we report the study of the change in electrical properties of semiconducting carbon nanotubes (CNTs) under uniaxial compressive deformations using the “Vienna ab initio simulation package” (VASP). We present an extension of density functional theory calculations to the electronic properties of the tubes, namely the density of states obtained for the optimized geometries of the tubes. There is an energy gap of 0.772 eV between occupied and unoccupied region in the optimized structure calculation. The band gap for the semi-conducting zigzag (10,0) CNTs decreases as the strain increases. It suggests that the semiconducting CNTs may become semimetal or metal upon deformation.

FIRST-PRINCIPLES STUDY OF ADSORPTION OF CN ON Cu(111)

2007 ◽  
Vol 06 (03) ◽  
pp. 523-529 ◽  
Author(s):  
WENZHEN LAI ◽  
HONG RAN ◽  
DAIQIAN XIE
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Stationary Points ◽  
Plane Wave Expansion ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Parallel Mode ◽  
Pseudo Potential

The adsorption of CN on Cu (111) has been investigated using density functional theory calculations based on plane-wave expansion and pseudo-potential treatment. Calculations within the generalized gradient approximation predicted a preference for CN in the fcc C -down site. No stationary points corresponding to pure parallel mode were found. But the tilted mode was found to be achievable. The calculated vibrational frequencies of CN were used to correctly discriminate between the adsorption sites.

scholarly journals Parachute structure trisiloxane surfactant: synthesis and its use in reverse flotation of iron ore

2021 ◽  
Author(s):  
Zhiqiang Huang ◽  
Shiyong Zhang ◽  
Vladimir E. Burov ◽  
Hongling Wang ◽  
Rukuan Liu ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reactivity ◽  
Froth Flotation ◽  
Density Functional Theory Calculations ◽  
Raw Material ◽  
Mulliken Charge ◽  
Single Element ◽  
Test Results ◽  
Functional Theory ◽  
Flotation Process

Abstract No single element has exerted such a deep influence on social organization of mankind as iron. Magnetite is concentrated by froth flotation and used as a raw material to produce iron. However, the conventional surfactants used in the flotation process often lead to the weak collecting performance due to their analogous alkyl hydrophobic group. Here, we report a new trisiloxane surfactant N-(β-aminoethyl)-γ-aminopropyltrisiloxane (AAT) in magnetite flotation, which was compared with the traditional collector dodecylamine (DA). The flotation test results showed that AAT had excellent collecting ability and selectivity for quartz against magnetite. Magnetite concentrate with TFe recovery of 84.79%, TFe grade of 68.84% and SiO2 grade of 6.15% was obtained by using 150 g/t AAT. Density functional theory calculations suggested reactive site of AAT was cationic –CH2N+H3 group, and AAT showed a higher positive grouping Mulliken charge and chemical reactivity that may promote its flotation performance.

scholarly journals Surprisingly facile CO2 insertion into cobalt alkoxide bonds: A theoretical investigation

2015 ◽  
Vol 11 ◽  
pp. 1340-1351 ◽  
Author(s):  
Willem K Offermans ◽  
Claudia Bizzarri ◽  
Walter Leitner ◽  
Thomas E Müller
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Density Functional Theory ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Activation Barrier ◽  
Density Functional Theory Calculations ◽  
Reaction Energy ◽  
Reaction Step ◽  
Functional Theory

Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory calculations to elucidate the reaction step of CO2 insertion into cobalt(III)–alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III)–alkoxide bond of [(2-hydroxyethoxy)CoIII(salen)(L)] complexes (salen = N,N”-bis(salicyliden-1,6-diaminophenyl)) is exothermic, whereby the exothermicity depends on the trans-ligand L. The more electron-donating this ligand is, the more exothermic the insertion step is. Interestingly, we found that the activation barrier decreases with increasing exothermicity of the CO2 insertion. Hereby, a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy.

CHARGE TRANSFER AND DIELECTRIC PROPERTIES OF TiO2–GRAPHENE COMPOSITES

2012 ◽  
Vol 02 (01) ◽  
pp. 1250004
Author(s):  
CAI-HUA ZHOU ◽  
QIAN XU ◽  
SHENG-TAO LI ◽  
XIANG ZHAO
Keyword(s):  
Charge Transfer ◽  
Dielectric Properties ◽  
Density Functional ◽  
Dielectric Constants ◽  
Potential Density ◽  
Functional Theory ◽  
Transfer Properties ◽  
Pseudo Potential ◽  
Interfacial Charge ◽  
Atomic Type

The electronic structures and dielectric properties of TiO2 –graphene composites are studied using pseudo-potential density functional theory. It is shown that interfacial charge transfer properties of graphene/ TiO2 are influenced by the atomic type on TiO2 surface. The interfacial interaction of graphene with Ti -terminated surface is so strong that it causes a buckling structural graphene, and the titanium atomic d electrons are transferred obviously from TiO2 to graphene. It is revealed that dielectric properties of the composites are greatly affected by both band structures and electronic transitions. Compared with bulk TiO2 , dielectric constants of TiO2 –graphene composites are significantly improved.

scholarly journals Coadsorption of NRR and HER intermediates determines the performance of Ru-N4 towards electrocatalytic N2 reduction

2021 ◽  
Author(s):  
Tongwei Wu ◽  
Marko Melander ◽  
Karoliina Honkala
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Atomic Scale ◽  
Potential Density ◽  
Functional Theory ◽  
Proton Donors ◽  
Constant Potential ◽  
Insight Into

Efficiency of the electrochemical N2 reduction reaction (NRR) to ammonia is seriously limited by the competing hydrogen evolution reaction (HER) but our current atomic-scale insight on the factors controlling HER/NRR competition are unknown. Herein we unveil the elementary mechanism, thermodynamics, and kinetics determining the HER/NRR selectivity on the state-of-the-art NRR electrocatalyst, Ru-N4 using constant potential density functional theory calculations (DFT). The calculations show that NRR and HER intermediates coadsorb on the catalyst where HER is greatly suppressed by the NRR intermediates. The first reaction step leading to either *NNH or *H determines the selectivity towards NRR or HER. Our results also demonstrate that an explicitly potential-dependent treatment of reaction kinetics is needed to understand NRR selectivity. We provide crucial insight into the complex NRR/HER competition and the role of non-innocent adsorbates, show the necessity of constant potential DFT calculations, and suggest that interfacial proton donors will improve NRR selectivity.

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