Effects of Oxygen Adsorption on Work Functions of Mo(110) Surface and Substrate

2010 ◽  
Vol 154-155 ◽  
pp. 832-839 ◽  
Author(s):  
Xu Huang ◽  
Zhen Zhen Weng ◽  
Gui Gui Xu ◽  
Zhi Gao Chen ◽  
Zhi Gao Huang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Oxygen Adsorption ◽  
Functional Theory ◽  
Oxygen Coverage ◽  
Probable Site ◽  
Density Surface ◽  
Work Functions ◽  
Adsorption Energies ◽  
The Relationship

Effects of oxygen atom adsorption on work functions of Mo(110) surface and substrate are investigated using first-principles methods based on density functional theory. The calculated results reveal that there exist a most probable site (named f1 site) in the surface oxygen adsorption on Mo(110) surface. Moreover, it is found that work functions of oxygen-adsorbed Mo(110) increase with increasing oxygen coverage, while the adsorption energies of oxygen decrease with increasing oxygen coverage. For a given oxygen coverage such as 0.333ML with surface f1 site, the work functions are insensitive to the distribution of oxygen atoms. In the meantime, the relationship among charge density, surface dipole density and the work function are discussed.

scholarly journals Effect of Defects on Spontaneous Polarization in Pure and Doped LiNbO3: First-Principles Calculations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 100 ◽  
Author(s):  
Weiwei Wang ◽  
Dahuai Zheng ◽  
Mengyuan Hu ◽  
Shahzad Saeed ◽  
Hongde Liu ◽  
...  
Keyword(s):  
Spontaneous Polarization ◽  
First Principles ◽  
Density Functional ◽  
Lattice Distortion ◽  
Stable Structure ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Specific Configuration ◽  
The Relationship

Numerous studies have indicated that intrinsic defects in lithium niobate (LN) dominate its physical properties. In an Nb-rich environment, the structure that consists of a niobium anti-site with four lithium vacancies is considered the most stable structure. Based on the density functional theory (DFT), the specific configuration of the four lithium vacancies of LN were explored. The results indicated the most stable structure consisted of two lithium vacancies as the first neighbors and the other two as the second nearest neighbors of Nb anti-site in pure LN, and a similar stable structure was found in the doped LN. We found that the defects dipole moment has no direct contribution to the crystal polarization. Spontaneous polarization is more likely due to the lattice distortion of the crystal. This was verified in the defects structure of Mg2+, Sc3+, and Zr4+ doped LN. The conclusion provides a new understanding about the relationship between defect clusters and crystal polarization.

scholarly journals First-principles study of organic molecule for corrosion inhibition

2019 ◽  
Vol 116 ◽  
pp. 00007
Author(s):  
Rachid Belkada ◽  
Dalila Hammoutène ◽  
Rahma Tibigui ◽  
Ikram Hadj-Said
Keyword(s):  
First Principles ◽  
Global Economy ◽  
Density Functional ◽  
Corrosion Inhibitors ◽  
Computational Techniques ◽  
Corrosion Properties ◽  
Functional Theory ◽  
Fundamental Level ◽  
Organic Inhibitors ◽  
The Relationship

The widespread use of steel in various industries, especially in the transportation of hydrocarbons and gas, has recently gained a potential interest to explore eco-friendly solutions against corrosion. In fact, the highly aggressive environment generates considerable losses that affect global economy of countries that are mainly depending on the production and transport of energy. In the field of corrosion inhibitors, most common method so far available for protection against corrosion relies on synthetic one. These are unfortunately harmful to the environment as well to the human health, however they remain the most popular and the most effective due to their cost, and their ease of application. One of the most challenging issues in this area is the accurate understanding and measure of the degree of the passivation of corrosion inhibitors, which is complex and depend on many factors such as the nature of the metal, the fluid, the electronic structure of the inhibitor, the temperature, the exposure time, and so on. Recently, organic inhibitors have become increasingly attractive due to their competitive character as compared to the synthetic ones. With the use of advanced computational techniques enhanced by the development of density functional theory (DFT), it becomes possible to identify and design at the fundamental level, novel corrosion inhibitor molecules as complementary well established tool beside to the experimental techniques, which are often very expensive and time-consuming. In this work, we explore by mean of DFT, the anti-corrosion effect of the Lawsone molecule (2-hydroxy-1,4-naphthoquinone) and some of its derivatives to clarify and understand the relationship at the fundamental level between the anti-corrosion properties and the structure of the molecule in contact with the iron.

Energetic Studies on the B Effect on the Oxidation of γ-TiAl Alloys

2014 ◽  
Vol 1052 ◽  
pp. 28-33 ◽  
Author(s):  
Guo Ying Zhang ◽  
Gui Li Liu ◽  
Jun Shan Bao ◽  
Chun Ming Liu ◽  
Hui Zhang
Keyword(s):  
Oxide Film ◽  
First Principles ◽  
Density Functional ◽  
Oxidation Process ◽  
Interstitial Site ◽  
Initial Oxidation ◽  
Functional Theory ◽  
Tial Alloys ◽  
Surface And Interface ◽  
Oxygen Coverage

The energetic study of B effects on the oxidation of γ-TiAl alloys are performed by using the first-principles method based on Density Functional Theory (DFT) in this paper. The surface and interface segregatation of B as well as of the surface adsorption of O are discussed. B is found to preferentially segregat to TiAl subsurface with respect to γ-TiAl bulk. The B segregation at surface decreases oxygen coverage in the initial oxidation process of γ –TiAl alloys, thereby it is beneficial to the decrease of the growth of γ–TiAl alloys oxide film. In the initial oxidation process, oxygen prefers to stay in the vicinity of surface Ti atoms, and B addition is beneficial for the decrease of the growth of A12O3 and TiO2. After the formation of Al2O3 oxide film, B is energetically favoured stayed at interstitial site of α-Al2O3 (0001)/γ-TiAl (111) interface, and enhances the adhesion of this interface.

First-principles study of nitrogen and carbon monoxide adsorptions on silicene

2016 ◽  
Vol 30 (25) ◽  
pp. 1650176 ◽  
Author(s):  
Shuying Zhong ◽  
Fanghua Ning ◽  
Fengya Rao ◽  
Xueling Lei ◽  
Musheng Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Charge Transfer ◽  
First Principles ◽  
Density Functional ◽  
Co Adsorption ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Adsorption Energies ◽  
Charge Calculations

Atomic adsorptions of N, C and O on silicene and molecular adsorptions of N2 and CO on silicene have been investigated using the density functional theory (DFT) calculations. For the atomic adsorptions, we find that the N atom has the most stable adsorption with a higher adsorption energy of 8.207 eV. For the molecular adsorptions, we find that the N2 molecule undergoes physisorption while the CO molecule undergoes chemisorption, the corresponding adsorption energies for N2 and CO are 0.085 and 0.255 eV, respectively. Therefore, silicene exhibits more reactivity towards the CO adsorption than the N2 adsorption. The differences of charge density and the integrated charge calculations suggest that the charge transfer for CO adsorption ([Formula: see text]0.015[Formula: see text]) is larger than that for N2 adsorption ([Formula: see text]0.005[Formula: see text]). This again supports that CO molecule is more active than N2 molecule when they are adsorbed onto silicene.

scholarly journals DIPEPTIDE ADSORPTION ON Si(100)-2 × 1 ASYMMETRIC SURFACE BY FIRST PRINCIPLES

2010 ◽  
Vol 21 (01) ◽  
pp. 97-106
Author(s):  
ETHEM AKTÜRK ◽  
OĞUZ GÜLSEREN ◽  
HANDAN ARKIN ◽  
TARIK ÇELIK
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Surface Interactions ◽  
Functional Theory ◽  
Surface Sites ◽  
Modify Surface ◽  
Adsorption Energies ◽  
Alanine Dipeptide ◽  
Molecule Surface

The adsorption of alanine dipeptide on a Si (100)-2 × 1 asymmetric surface is studied by using pseudopotential plane wave approach based on Density Functional Theory (DFT). Adsorption energies for different surface sites of various conformations are calculated and the groove site is found to be energetically most favorable. We observed that the molecule-surface interactions might modify surface reconstruction: asymmetric surface dimers reconstruct to asymmetric dimers in opposite directions doubling the surface periodicity, which in turn gives the surface metallic properties.

First Principles Calculation on Adsorption of S on Fe(100) with Different Pressure

2012 ◽  
Vol 217-219 ◽  
pp. 1811-1814
Author(s):  
Xue Tao Hu ◽  
Qiang Luo ◽  
Zeng Ling Ran
Keyword(s):  
Hydrostatic Pressure ◽  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Hollow Site ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Adsorption Energies

Using periodic density functional theory within the generalized-gradient approximation to electron exchange and correlation, we have studied S adsorption four-fold hollow site on Fe(100) in different hydrostatic pressure. We find that the adsorption height decreases with hydrostatic pressure increasing is non-monotonic. The adsorption energy decreases with an increase with pressure is monotonic and we have obtained density of states is almost unchanged, the adsorption energy change is mainly caused by lattice deformation in the hydrostatic pressure, and the adsorption energies increase linearly with pressure.

DENSITY FUNCTIONAL THEORY STUDIES ON THE ADSORPTION OF 4-METHYLBENZENETHIOL AND 4-ETHYLBENZENETHIOL MOLECULES ON Au(111) SURFACE

2014 ◽  
Vol 21 (06) ◽  
pp. 1450087 ◽  
Author(s):  
XIAOLIANG FANG ◽  
XIAOLI FAN ◽  
RUNXIN RAN ◽  
PIN XIAO
Keyword(s):  
Density Functional Theory ◽  
Tilt Angle ◽  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
Energy Calculation ◽  
Functional Theory ◽  
Calculation Results ◽  
Adsorption Energies ◽  
First Principles Method

The nondissociative and dissociated adsorptions of 4-methylbenzenethiol (4-MBT) and 4-ethylbenzenethiol (4-EBT) on Au (111) surface were studied by applying the first-principles method based on density functional theory. The effects of coverage and vdW interactions on adsorptions were investigated. Adsorption energies and tilt angles of both 4-MBT and 4-EBT decrease with the increase of the coverage, and vdW interactions can affect the adsorption configuration and energy. More importantly, in the case of 4-EBT adsorption, we have studied the effects of ethyl group's orientation on the adsorption configuration and energy. Calculation results show that ethyl group's orientation has little effect on the adsorption energy, but changes the tilt angle by around 7°. Our calculations provide a deeper elucidation of the observed adsorption configuration for 4-EBT on Au (111).

CO Adsorption on the AunS(n=1~6) Clusters: The First-Principles Study

2011 ◽  
Vol 341-342 ◽  
pp. 42-47
Author(s):  
Shui Lian Chi ◽  
Ming Chen ◽  
Song Lin Peng
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Population Analysis ◽  
Co Adsorption ◽  
Bimetallic Clusters ◽  
Mulliken Population Analysis ◽  
Mulliken Population ◽  
Functional Theory ◽  
Au Clusters ◽  
Adsorption Energies

Density functional theory (DFT) calculations are performed to investigate CO bonded on the AunS (n=1~6) bimetallic clusters. It is found that the adsorption energies of CO on the AunS(n=1~6) clusters are greater than those on the pure Au clusters of corresponding sizes. This means that doped S atom can enhance CO adsorption on the Au clusters. Furthermore, through the Mulliken population analysis, we can see that charges transfer from the Au clusters to S atom, while charges donate to the Au clusters from the CO in CO/AunS sytem.

DFT Study of Chemisorbed Atomic Oxygen Inducing Co Segregation in CoNi(111) Alloy

2016 ◽  
Vol 850 ◽  
pp. 362-369 ◽  
Author(s):  
Yan Lin Yu ◽  
Li Gen Wang ◽  
Wei Xiao ◽  
Guo Jie Huang
Keyword(s):  
Hydrogen Evolution ◽  
Density Functional ◽  
Atomic Oxygen ◽  
Oxygen Adsorption ◽  
Reaction Conditions ◽  
Functional Theory ◽  
Coverage Dependence ◽  
Theoretical Investigations ◽  
Oxygen Coverage ◽  
The Difference

Chemisorbed atomic oxygen inducing Co segregation in CoNi (111) alloy is studied using periodic self-consistent density functional theory (DFT) calculations. In particular, the coverage dependence and possible adsorption-induced segregation phenomena are addressed by investigating segregation energies (the difference in calculated total free energy between surface sites and bulk-like sites) of isolated Co in CoNi (111) alloy. In agreement with previous experimental and theoretical investigations, segregation of Co is found to be oxygen-coverage dependent. While for ‘clean’ CoNi (111), Co prefers to be in the bulk. In the presence of more than 2/9 ML of oxygen, Co segregates to the surface. The analysis of oxygen adsorption trends and surface electronic structures explains the change in the local atomic arrangement which is expected to occur on the surface of alloys under reaction conditions. Our predictions for the high oxygen coverage cases are particularly relevant in underlining the importance of segregation phenomena to the hydrogen evolution performance of CoNi alloy hydrogen evolution electrode.

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