scholarly journals Theoretical Investigation of HER Mechanism Using Density Functional and Ab Initio Calculations

2021 ◽  
Author(s):  
Rory Ma ◽  
Kiryong Hong
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
Density Functional

scholarly journals Theoretical investigation of the side-chain mechanism of the MTO process over H-SSZ-13 using DFT and ab initio calculations

2021 ◽  
Author(s):  
Michal Fečík ◽  
Philipp N. Plessow ◽  
Felix Studt
Keyword(s):  
Density Functional Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Large Cluster ◽  
Side Chain ◽  
Chain Mechanism ◽  
Functional Theory ◽  
Mto Process

The side-chain mechanism of the methanol-to-olefins process over the H-SSZ-13 acidic zeolite was investigated using periodic density functional theory with corrections from highly accurate ab intio calculations on large cluster models.

scholarly journals Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Valery Davydov ◽  
Evgenii Roginskii ◽  
Yuri Kitaev ◽  
Alexander Smirnov ◽  
Ilya Eliseyev ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Characteristics ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
Short Period ◽  
Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

scholarly journals Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5481
Author(s):  
Marcin Sikora ◽  
Anna Bajorek ◽  
Artur Chrobak ◽  
Józef Deniszczyk ◽  
Grzegorz Ziółkowski ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Plane Waves ◽  
Full Potential ◽  
Theory Approach ◽  
Xps Spectra

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

scholarly journals Polydopamine and eumelanin molecular structures investigated with ab initio calculations

2017 ◽  
Vol 8 (2) ◽  
pp. 1631-1641 ◽  
Author(s):  
Chun-Teh Chen ◽  
Francisco J. Martin-Martinez ◽  
Gang Seob Jung ◽  
Markus J. Buehler
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Molecular Structures ◽  
Brute Force ◽  
Functional Theory

A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin.

Ligand field fine-tuning on the modulation of the magnetic properties and relaxation dynamics of dysprosium(iii) single-ion magnets (SIMs): synthesis, structure, magnetism and ab initio calculations

2017 ◽  
Vol 5 (6) ◽  
pp. 1369-1382 ◽  
Author(s):  
Sheng Zhang ◽  
Haipeng Wu ◽  
Lin Sun ◽  
Hongshan Ke ◽  
Sanping Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
Fine Tuning ◽  
Ligand Field ◽  
Relaxation Dynamics ◽  
Controllable Synthesis

For dysprosium(iii) single-ion magnets (SIMs), it is crucial to explore their controllable synthesis and conduct a systematic theoretical investigation.

scholarly journals Armchair Boron Nitride nanotubes—heterocyclic molecules interactions: A computational description

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Ernesto Chigo Anota ◽  
Gregorio Hernández Cocoletzi ◽  
Andres Manuel Garay Tapia
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Boron Nitride Nanotubes ◽  
Functional Theory ◽  
Heterocyclic Molecules ◽  
Non Covalent Interactions ◽  
Covalent Interactions

AbstractAb-initio calculations using density functional theory (DFT) are used to investigate the non-covalent interactions between single wall armchair boron nitride nanotubes (BNNTs) with open ends and several heterocyclic molecules: thiophene (T; C

Ab initio calculations of quantum transport of Au–GaN–Au nanoscale junctions

RSC Advances ◽  
2014 ◽  
Vol 4 (94) ◽  
pp. 51838-51844 ◽  
Author(s):  
Tian Zhang ◽  
Yan Cheng ◽  
Xiang-Rong Chen
Keyword(s):  
Density Functional Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Transport Properties ◽  
Quantum Transport ◽  
Electronic Transport ◽  
Density Functional ◽  
Function Method ◽  
Functional Theory ◽  
Non Equilibrium Green’S Function

We investigate the contact geometry and electronic transport properties of a GaN pair sandwiched between Au electrodes by performing density functional theory plus the non-equilibrium Green's function method.

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