scholarly journals Vibrational Study of the Hydrogen Adsorption on the Missing Row Platinum (110) Surface

2020 ◽  
Vol 30 (1) ◽  
pp. 27
Author(s):  
Tran Thi Thu Hanh ◽  
Nguyen Van Hoa
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Ultrahigh Vacuum ◽  
Adsorption Model ◽  
Platinum Surface ◽  
Functional Theory ◽  
Vibrational Study ◽  
The Density Functional Theory

The hydrogen vibration was investigated to analyze its affect on the hydrogen adsorption on the missing row platinum surface (H/Pt(110)-(1\(\times\)2) model) in the ultrahigh vacuum (UHV). The density functional theory (DFT) combined with the approximation oscillation of the hydrogen atom on the surface was used. When the hydrogen coverage ΘH on the surface is 100% (\(\Theta\) = 1 ML), and taking into account the vibrational effect, the bond formed at the edge of the first layer (short bridge) is the most stable site. The vibrational effect on the adsorption model H/Pt(110)-(1\(\times\)2) is significant.

DECOMPOSITION OF SiH4 ON THE SA TYPE STEPPED Si(100) SURFACE

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1401-1407 ◽  
Author(s):  
ŞENAY KATIRCIOĞlu ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Reaction Path ◽  
Density Functional Theory Method ◽  
Dissociative Adsorption ◽  
Theory Method ◽  
Functional Theory ◽  
Initial Stage ◽  
The Density Functional Theory

The density functional theory method is used to explore the mechanism of dissociative adsorption of silane (SiH4) on the SA type stepped Si(100) surface. Two reaction paths are described that produce silyl (SiH3) and hydrogen atom fragments adsorbed on the dimer bonds present on each terrace. It has been found that the initial stage of the dissociation of SiH4 on the SA type stepped Si(100) surface shows similarity to the dissociation of SiH4 on the flat Si(100) surface; SiH3 and hydrogen fragments bond to the Si dimer atoms by following the first reaction path.

scholarly journals SIMULASI PERUBAHAN DENSITAS MUATAN ADSORPSI ATOM HIDROGEN-GRAFENA DENGAN TEORI FUNGSI KERAPATAN

2018 ◽  
Vol 3 (2) ◽  
pp. 179-184
Author(s):  
Albert Zicko Johannes
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Charge Density ◽  
Density Functional ◽  
Structural Changes ◽  
Density Functional Theory Method ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Center Position

Abstrak Peristiwa adsorpsi atom Hidrogen pada Grafena menyebabkan terjadinya perubahan struktur Grafena. Perubahan ini mempengaruhi keadaan densitas muatan Grafena. Pada simulasi ini posisi atom Hidrogen pada permukaan lembaran Grafena divariasikan, yaitu pada posisi tepat di atas atom Karbon (Top), posisi di tengah antara dua atom Karbon (Bridge), dan posisi pusat struktur heksagonal (Hollow). Simulasi dilakukan dengan metode Teori Fungsi Kerapatan dengan model Grafena ukuran 2x2. Hasil yang diperoleh menunjukkan adsorpsi atom Hidrogen memilih posisi Top sebagai yang paling stabil dibandingkan dengan posisi Bridge dan Hollow. Hasil dari posisi Top menunjukkan elektron dari atom Hidrogen digunakan mengikat Grafena dengan energi ikat sebesar -1.7 eV. Perubahan densitas muatan menunjukkan terjadinya perpindahan elektron menuju Grafena disertai transformasi isosurface yang unik untuk setiap posisi atom Hidrogen dengan perubahan terbesar terjadi pada posisi Top.  Kata kunci: Densitas muatan, Grafena, Adsorpsi, Teori Fungsi Kerapatan  Abstract [Title: The Simulation of Charge Density Diffrential for Hydrogen Atom - Graphene Adsorption with Density Functional Theory] Hydrogen atom adsorption on Graphene cause structural changes. This change affect Graphene charge density. In this simulation the position of Hydrogen atom on the surface of Graphene sheet are varied out, which is on the position directly above the Carbon atom (Top), the position on the middle between two Carbon atoms (Bridge), and the center position of the hexagonal structure (Hollow). The simulation is done by the Density Functional Theory method with a 2x2 size Graphene model. The results obtained showed that Hydrogen atom adsorption chose the Top position as the most balanced compared with the position of Bridge and Hollow. The results from the Top position indicate that electrons from Hydrogen atom are used to bind the Graphene with binding energy of -1.7 eV. The charge density differential indicate the occurrence of electron transfer towards Graphene accompanied by a transformation of the isosurface that are unique for each Hydrogen atom positions with the biggest change is shown in the Top position.  Keywords: Charge Density, Graphene, Adsorption, Density Functional Theory

scholarly journals Hydrogenated Microstructure and Its Hydrogenation Properties: A Density Functional Theory Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Abdus Salam ◽  
Bawadi Abdullah ◽  
Suriati Sufian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Hydrogen Desorption ◽  
Spectroscopic Techniques ◽  
Functional Theory ◽  
Hydrogen Saturation ◽  
Analysis Technique ◽  
The Density Functional Theory ◽  
Nano Grains

The relationship between microstructure and hydrogenation properties of the mixed metals has been investigated via different spectroscopic techniques and the density functional theory (DFT). FESEM and TEM analyses demonstrated the nano-grains of Mg2NiH4and MgH2on the hydrogenated microstructure of the adsorbents that were confirmed by using XPS analysis technique. SAED pattern of hydrogenated metals attributed the polycrystalline nature of mixed metals and ensured the hydrogenation to Mg2NiH4and MgH2compounds. Flower-like rough surface of mixed metals showed high hydrogenation capacity. The density functional theory (DFT) predicted hydrogenation properties; enthalpy and entropy changes of hydrogenated microstructure of MgH2and Mg2NiH4are −62.90 kJ/mol, −158 J/mol·K and −52.78 kJ/mol, −166 J/mol·K, respectively. The investigation corresponds to the hydrogen adsorption feasibility, reversible range hydrogenation thermodynamics, and hydrogen desorption energy of 54.72 kJ/mol. DFT predicted IR band for MgH2and Mg2NiH4attributed hydrogen saturation on metal surfaces.

scholarly journals SIMULASI PERUBAHAN DENSITAS MUATAN ADSORPSI ATOM HIDROGEN-GRAFENA DENGAN TEORI FUNGSI KERAPATAN

2018 ◽  
Vol 3 (3) ◽  
pp. 179-184
Author(s):  
Albert Zicko Johannes
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Charge Density ◽  
Density Functional ◽  
Structural Changes ◽  
Density Functional Theory Method ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Center Position

Abstrak Peristiwa adsorpsi atom Hidrogen pada Grafena menyebabkan terjadinya perubahan struktur Grafena. Perubahan ini mempengaruhi keadaan densitas muatan Grafena. Pada simulasi ini posisi atom Hidrogen pada permukaan lembaran Grafena divariasikan, yaitu pada posisi tepat di atas atom Karbon (Top), posisi di tengah antara dua atom Karbon (Bridge), dan posisi pusat struktur heksagonal (Hollow). Simulasi dilakukan dengan metode Teori Fungsi Kerapatan dengan model Grafena ukuran 2x2. Hasil yang diperoleh menunjukkan adsorpsi atom Hidrogen memilih posisi Top sebagai yang paling stabil dibandingkan dengan posisi Bridge dan Hollow. Hasil dari posisi Top menunjukkan elektron dari atom Hidrogen digunakan mengikat Grafena dengan energi ikat sebesar -1.7 eV. Perubahan densitas muatan menunjukkan terjadinya perpindahan elektron menuju Grafena disertai transformasi isosurface yang unik untuk setiap posisi atom Hidrogen dengan perubahan terbesar terjadi pada posisi Top.  Kata kunci: Densitas muatan, Grafena, Adsorpsi, Teori Fungsi Kerapatan  Abstract [Title: The Simulation of Charge Density Diffrential for Hydrogen Atom - Graphene Adsorption with Density Functional Theory] Hydrogen atom adsorption on Graphene cause structural changes. This change affect Graphene charge density. In this simulation the position of Hydrogen atom on the surface of Graphene sheet are varied out, which is on the position directly above the Carbon atom (Top), the position on the middle between two Carbon atoms (Bridge), and the center position of the hexagonal structure (Hollow). The simulation is done by the Density Functional Theory method with a 2x2 size Graphene model. The results obtained showed that Hydrogen atom adsorption chose the Top position as the most balanced compared with the position of Bridge and Hollow. The results from the Top position indicate that electrons from Hydrogen atom are used to bind the Graphene with binding energy of -1.7 eV. The charge density differential indicate the occurrence of electron transfer towards Graphene accompanied by a transformation of the isosurface that are unique for each Hydrogen atom positions with the biggest change is shown in the Top position.  Keywords: Charge Density, Graphene, Adsorption, Density Functional Theory

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

scholarly journals Study on the interaction between catechin and cholesterol by the density functional theory

2020 ◽  
Vol 18 (1) ◽  
pp. 357-368
Author(s):  
Kaiwen Zheng ◽  
Kai Guo ◽  
Jing Xu ◽  
Wei Liu ◽  
Junlang Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Micelle Formation ◽  
Aromatic Rings ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractCatechin – a natural polyphenol substance – has excellent antioxidant properties for the treatment of diseases, especially for cholesterol lowering. Catechin can reduce cholesterol content in micelles by forming insoluble precipitation with cholesterol, thereby reducing the absorption of cholesterol in the intestine. In this study, to better understand the molecular mechanism of catechin and cholesterol, we studied the interaction between typical catechins and cholesterol by the density functional theory. Results show that the adsorption energies between the four catechins and cholesterol are obviously stronger than that of cholesterol themselves, indicating that catechin has an advantage in reducing cholesterol micelle formation. Moreover, it is found that the molecular interactions of the complexes are mainly due to charge transfer of the aromatic rings of the catechins as well as the hydrogen bond interactions. Unlike the intuitive understanding of a complex formed by hydrogen bond interaction, which is positively correlated with the number of hydrogen bonds, the most stable complexes (epicatechin–cholesterol or epigallocatechin–cholesterol) have only one but stronger hydrogen bond, due to charge transfer of the aromatic rings of catechins.

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