Calculations of Thermodynamic Characteristics of Vapor Interlayers with the Use of Gradient and Integral Density Functional Theories and Nudged Elastic Band Method

2021 ◽  
Vol 83 (5) ◽  
pp. 558-565
Author(s):  
L. A. Gosteva ◽  
A. K. Shchekin
Keyword(s):  
Density Functional ◽  
Thermodynamic Characteristics ◽  
Elastic Band ◽  
Integral Density ◽  
Band Method

scholarly journals Ab Initio Investigation of Helium Mobility in La2Zr2O7 Pyrochlore

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 667
Author(s):  
Yanxia Lu ◽  
Qing Peng ◽  
Chenguang Liu
Keyword(s):  
Nuclear Waste ◽  
Density Functional ◽  
Minimum Energy ◽  
Elastic Band ◽  
Waste Forms ◽  
Band Method ◽  
And Migration ◽  
High Level ◽  
Migration Pathways ◽  
Nuclear Waste Forms

The α-decay of incorporated actinides continuously produces helium, resulting in helium accumulation and causing security concerns for nuclear waste forms. The helium mobility is a key issue affecting the accumulation and kinetics of helium. The energy barriers and migration pathways of helium in a potential high-level nuclear waste forms, La2Zr2O7 pyrochlore, have been investigated in this work using the climbing image nudged elastic band method with density functional theory. The minimum energy pathway for helium to migrate in La2Zr2O7 is identified as via La–La interstitial sites with a barrier of 0.46 eV. This work may offer a theoretical foundation for further prospective studies of nuclear waste forms.

scholarly journals A combined DFT/topological analysis approach for modeling disordered solid electrolytes

2019 ◽  
Vol 201 ◽  
pp. 02005 ◽  
Author(s):  
Pavel Zolotarev ◽  
Nadezhda Nekrasova ◽  
Andrey Golov ◽  
Roman Eremin
Keyword(s):  
Density Functional ◽  
Topological Analysis ◽  
Density Functional Theory Calculations ◽  
Topological Descriptors ◽  
Elastic Band ◽  
Functional Theory ◽  
Ion Migration ◽  
Energy Characteristics ◽  
The Density Functional Theory ◽  
Band Method

In the scope of this study, the Ag2S·CdS·3SnS2 solid electrolyte disordered in the Cd/Sn sublattice is explored by means of the approach involving configurational space (CS) setting and first-principles calculations. Within the density functional theory calculations on the CS, the absolute differences in Ag vacancy formation energies up to 2.6 eV/cell were obtained for possible Cd/Sn dispositions. Subsequently, silver ion migration was modeled using the nudged elastic band method. The migration energies in the range of 0.250 to 2.993 eV/cell were obtained. By application of topological descriptors, namely, the relative disposition of Cd atoms and the number of Cd atoms in the vicinity of Ag vacancy, the reliable correlations were obtained between the Cd/Sn relative disposition and the calculated energy characteristics.

Investigation of the Barrier Heights for Dissociative Adsorption of HF on SiC Surfaces in the Catalyst-Referred Etching Process

2014 ◽  
Vol 778-780 ◽  
pp. 726-729 ◽  
Author(s):  
Pho Van Bui ◽  
Kouji Inagaki ◽  
Yasuhisa Sano ◽  
Kazuto Yamauchi ◽  
Yoshitada Morikawa
Keyword(s):  
Barrier Height ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
Etching Process ◽  
Care Process ◽  
Generalized Gradient ◽  
Elastic Band ◽  
Barrier Heights ◽  
The Density Functional Theory ◽  
Band Method

We have developed a novel abrasive-free planarization method, which we term catalyst-referred etching (CARE). In silicon carbide (SiC) CARE, Pt is used as a catalyst and HF solution is used as an etchant. CARE produces a crystallographically undamaged and smooth SiC surface. To understand the removal mechanism at the topmost surface of SiC in the CARE process, we performed first-principles reaction path simulations using the simulation tool for atom technology (STATE) program package. These calculations are based on the density functional theory within the generalized gradient approximation of Perdew et al. The barrier height of the dissociative adsorption of HF on a SiC surface was evaluated by the climbing image nudged elastic band method. We present simulation results for the initial stages of the etching process. The reaction barrier height for adsorption of the first HF is 1.2 eV.

scholarly journals Adsorption and Surface Diffusion of Metals on α-Al2O3 for Advanced Manufacturing Applications

JOM ◽  
2021 ◽  
Vol 73 (4) ◽  
pp. 1062-1070
Author(s):  
Austin Biaggne ◽  
Gregory Noble ◽  
Lan Li
Keyword(s):  
Surface Diffusion ◽  
Density Functional ◽  
Advanced Manufacturing ◽  
Elastic Band ◽  
Adsorption Sites ◽  
Band Method ◽  
Diffusion Paths ◽  
Adsorption Energies ◽  
Manufacturing Applications ◽  
Α Al2o3

AbstractThe adsorption and diffusion of Mo and Nb adatoms on the $$\alpha$$ α -Al2O3 (0001) surface were explored using density functional theory-based methods. Adsorption energies of Mo and Nb adatoms at minima sites on the surface were determined. Mo and Nb adatoms prefer to adsorb to the same locations on the surface, and larger adsorption energies calculated for Nb compared to Mo indicate that Nb adatom-surface interactions are stronger than Mo. Using minima adsorption sites as initial and final locations for surface diffusion, energy barriers for diffusion were calculated using the nudged elastic band method. Overall, Mo and Nb follow roughly the same diffusion paths. The diffusion pre-factors for Mo and Nb are similar; however, Mo diffusion has a lower energy barrier and thus a larger diffusion coefficient compared with Nb. These results provide insight into the role of surface diffusion of Mo and Nb adatoms during advanced manufacturing processes.

Ab initio calculations of Na and Ni diffusion in NaNi1/2Mn1/2O2 and NaNi1/3Mn1/3Co1/3O2 for Na-ion batteries

2014 ◽  
Vol 28 (25) ◽  
pp. 1450202 ◽  
Author(s):  
J. J. Shi ◽  
G. Q. Yin ◽  
L. M. Jing ◽  
J. Guan ◽  
M. P. Wu ◽  
...  
Keyword(s):  
Cathode Materials ◽  
Energy Barrier ◽  
Density Functional ◽  
Electrode Materials ◽  
Elastic Band ◽  
Nickel Ion ◽  
Functional Theory ◽  
Layered Cathode Materials ◽  
Band Method ◽  
Sodium Diffusion

In this paper, sodium and nickel ion dynamics in layered cathode materials of NaNi 1/2 Mn 1/2 O 2 and NaNi 1/3 Mn 1/3 Co 1/3 O 2 for Na -ion battery applications were investigated using first principles based on density functional theory. The diffusion pathways for sodium and nickel migration inside the layered cathode materials were optimized and their energy barriers were calculated based on the nudged elastic band method. The energy barrier of Na diffusion in NaNi 1/2 Mn 1/2 O 2 and NaNi 1/3 Mn 1/3 Co 1/3 O 2 is about 1.0 eV. However, when the Ni is located at the Na layer, i.e. occupying the Na position, the energy barrier for Ni diffusion inside the layered cathode materials is about 0.36 eV, which indicates that Ni will diffuse to the surface of electrode materials, thus will block or slow down the sodium diffusion, limiting the battery performance.

First-Principles Study of Reaction Process of SiC and HF Molecules in Catalyst-Referred Etching

2012 ◽  
Vol 523-524 ◽  
pp. 173-177 ◽  
Author(s):  
Pho Van Bui ◽  
Kouji Inagaki ◽  
Yasuhisa Sano ◽  
Kazuto Yamauchi ◽  
Yoshitada Morikawa
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Pt Catalyst ◽  
Care Process ◽  
Generalized Gradient ◽  
Elastic Band ◽  
Functional Theory ◽  
Barrier Heights ◽  
The Density Functional Theory ◽  
Band Method

We have developed a novel abrasive-free planarization method, which we term catalyst-referred etching (CARE). In SiC CARE, Pt is used as a catalyst and HF solution is used as an etchant. CARE produces a crystallographically undamaged and smooth SiC surface. To understand the removal mechanism at the topmost surface of SiC in the CARE process, we performed first-principles reaction path simulations using the Simulation Tool for Atom Technology (STATE) program package. These calculations are based on the density functional theory within the generalized gradient approximation of Perdew et al. The barrier height is evaluated by the climbing image nudged elastic band method. We present simulation results for the initial stages of the etching process. The reaction barrier heights for the adsorption of HF molecules on the first, second, and third Si–C bonds at the edge of the topmost Si-face are 1.8, 1.9, and 1.2 eV, respectively. These barrier heights are reasonably small for a consideration of effect of the Pt catalyst.

Nudged Elastic Band Method for Molecular Reactions Using Energy-Weighted Springs Combined with Eigenvector Following

2021 ◽  
Author(s):  
Vilhjálmur Ásgeirsson ◽  
Benedikt Orri Birgisson ◽  
Ragnar Bjornsson ◽  
Ute Becker ◽  
Frank Neese ◽  
...  
Keyword(s):  
Elastic Band ◽  
Band Method ◽  
Molecular Reactions

scholarly journals CH4 dissociation on the Pd/Cu(111) surface alloy: A DFT study

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 790-798
Author(s):  
Aykan Akça
Keyword(s):  
Catalytic Activity ◽  
Adsorption Energy ◽  
Lower Cost ◽  
Relative Energy ◽  
Catalyst Design ◽  
Elastic Band ◽  
Efficient Catalyst ◽  
Energy Diagram ◽  
Band Method ◽  
Pure Cu

AbstractThe periodic four-layered model of the pure Cu(111) surface has been considered, and the effect of doping with palladium on CH4 dissociation has been investigated. The most stable adsorption geometries of CHx species (x = 1–4) and H atom on the PdCu(111) and pure Cu(111) surfaces have been obtained. Their computed adsorption energy results on the pure Cu(111) surface have been compared with the previously reported studies. Then, transition state geometries of CH4 dehydrogenation steps on both surfaces were calculated by the climbing image nudged elastic band method. Finally, the relative energy diagram for CH4 complete dehydrogenation has been represented. The results show that the PdCu(111) surface is more favorable than the Cu(111) surface in terms of the activation energies. The addition of Pd atoms to the Cu(111) surface significantly improves the catalytic activity. This knowledge can enable an efficient catalyst design at a lower cost using different strategies.

Searching for Saddle Points by Using the Nudged Elastic Band Method:  An Implementation for Gas-Phase Systems

2006 ◽  
Vol 2 (4) ◽  
pp. 895-904 ◽  
Author(s):  
Núria González-García ◽  
Jingzhi Pu ◽  
Àngels González-Lafont ◽  
José M. Lluch ◽  
Donald G. Truhlar
Keyword(s):  
Gas Phase ◽  
Saddle Points ◽  
Elastic Band ◽  
Band Method ◽  
Phase Systems

scholarly journals Revisiting the Volmer–Heyrovský mechanism of hydrogen evolution on a nitrogen doped carbon nanotube: constrained molecular dynamics versus the nudged elastic band method

2020 ◽  
Vol 22 (19) ◽  
pp. 10536-10549 ◽  
Author(s):  
Rasmus Kronberg ◽  
Heikki Lappalainen ◽  
Kari Laasonen
Keyword(s):  
Hydrogen Evolution ◽  
Electrochemical Reactions ◽  
Direct Simulation ◽  
Elastic Band ◽  
Nitrogen Doped ◽  
Solvent Dynamics ◽  
Rigorous Description ◽  
Band Method ◽  
Nitrogen Doped Carbon ◽  
Explicit Dynamic

This study presents the first direct simulation of the hydrogen evolution reaction using a fully explicit, dynamic DFT approach and highlights the importance of incorporating solvent dynamics in the rigorous description of electrochemical reactions.

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