Model forCdefect on Si(100):  The dissociative adsorption of a single water molecule on two adjacent dimers

2003 ◽  
Vol 67 (15) ◽  
Author(s):  
M. Z. Hossain ◽  
Y. Yamashita ◽  
K. Mukai ◽  
J. Yoshinobu
Keyword(s):  
Water Molecule ◽  
Dissociative Adsorption ◽  
Single Water Molecule

scholarly journals Understanding Cement Hydration of Cemented Paste Backfill: DFT Study of Water Adsorption on Tricalcium Silicate (111) Surface

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 202 ◽  
Author(s):  
Chongchong Qi ◽  
Lang Liu ◽  
Jianyong He ◽  
Qiusong Chen ◽  
Li-Juan Yu ◽  
...  
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Dissociative Adsorption ◽  
Molecular Adsorption ◽  
Cemented Paste Backfill ◽  
Adsorption Mechanisms ◽  
Paste Backfill ◽  
Single Water Molecule

Understanding cement hydration is of crucial importance for the application of cementitious materials, including cemented paste backfill. In this work, the adsorption of a single water molecule on an M3-C3S (111) surface is investigated using density functional theory (DFT) calculations. The adsorption energies for 14 starting geometries are calculated and the electronic properties of the reaction are analysed. Two adsorption mechanisms, molecular adsorption and dissociative adsorption, are observed and six adsorption configurations are found. The results indicate that spontaneous dissociative adsorption is energetically favored over molecular adsorption. Electrons are transferred from the surface to the water molecule during adsorption. The density of states (DOS) reveals the bonding mechanisms between water and the surface. This study provides an insight into the adsorption mechanism at an atomic level, and can significantly promote the understanding of cement hydration within such systems.

scholarly journals Role of Mg Impurity in the Water Adsorption over Low-Index Surfaces of Calcium Silicates: A DFT-D Study

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 665
Author(s):  
Chongchong Qi ◽  
Qiusong Chen ◽  
Andy Fourie
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Water Adsorption ◽  
Dissociative Adsorption ◽  
Mg Doping ◽  
Calcium Silicates ◽  
Single Water Molecule ◽  
The Impact ◽  
Mg Doped

Calcium silicates are the most predominant phases in ordinary Portland cement, inside which magnesium is one of the momentous impurities. In this work, using the first-principles density functional theory (DFT), the impurity formation energy (Efor) of Mg substituting Ca was calculated. The adsorption energy (Ead) and configuration of the single water molecule over Mg-doped β-dicalcium silicate (β-C2S) and M3-tricalcium silicate (M3-C3S) surfaces were investigated. The obtained Mg-doped results were compared with the pristine results to reveal the impact of Mg doping. The results show that the Efor was positive for all but one of the calcium silicates surfaces (ranged from −0.02 eV to 1.58 eV), indicating the Mg substituting for Ca was not energetically favorable. The Ead of a water molecule on Mg-doped β-C2S surfaces ranged from –0.598 eV to −1.249 eV with the molecular adsorption being the energetically favorable form. In contrast, the Ead on M3-C3S surfaces ranged from −0.699 eV to −4.008 eV and the more energetically favorable adsorption on M3-C3S surfaces was dissociative adsorption. The influence of Mg doping was important since it affected the reactivity of surface Ca/Mg sites, the Ead of the single water adsorption, as well as the adsorption configuration compared with the water adsorption on pristine surfaces.

The adsorption of a single water molecule on low-index C3S surfaces: A DFT approach

2019 ◽  
Vol 471 ◽  
pp. 658-663 ◽  
Author(s):  
Yue Zhang ◽  
Xinying Lu ◽  
Dongsheng Song ◽  
Songbai Liu
Keyword(s):  
Water Molecule ◽  
Single Water Molecule

A Study of Adsorption Behavior of Single Water Molecule on the Surface of Polyhedral Oligomeric Silsesquioxanes

2015 ◽  
Vol 26 (2) ◽  
pp. 541-550
Author(s):  
Li Wang ◽  
Rui-Xia Song ◽  
Min-Si Xin ◽  
Yan Meng ◽  
Wei Feng ◽  
...  
Keyword(s):  
Water Molecule ◽  
Adsorption Behavior ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Single Water Molecule

The Structure and Properties of Water

2016 ◽  
Author(s):  
Bruce C. Bunker ◽  
William H. Casey
Keyword(s):  
Hydrogen Bonding ◽  
Water Molecule ◽  
Bond Length ◽  
Electrostatic Interactions ◽  
Structure And Properties ◽  
Oxygen Anion ◽  
Lone Pairs ◽  
Tetrahedral Angle ◽  
Oxide Phases ◽  
Single Water Molecule

Water is one of the most complex fluids on Earth. Even after intense study, there are many aspects regarding the structure, properties, and chemistry of water that are not well understood. In this chapter, we highlight the attributes of water that dictate many of the reactions that take place between water and oxides. We start with a single water molecule and progress to water clusters, then finally to extended liquid and solid phases. This chapter provides a baseline for evaluating what happens when water encounters simple ions, soluble oxide complexes called hydrolysis products, and extended oxide phases. The primary phenomenon highlighted in this chapter is hydrogen bonding. Hydrogen bonding dominates the structure and properties of water and influences many water–oxide interactions. A single water molecule has eight valence electrons around a central oxygen anion. These electrons are contained in four sp3-hybridized molecular orbitals arranged as lobes that extend from the oxygen in a tetrahedral geometry. Each orbital is occupied by two electrons. Two of the lobes are bonded to protons; the other two lobes are referred to as lone pairs of electrons. The H–O–H bond angle of 104.5° is close to the tetrahedral angle of 109.5°. The O–H bond length in a single water molecule is 0.96 Ǻ. It is important to recognize that this bond length is really a measure of the electron density associated with the oxygen lone pair bonded to the proton. This is because a proton is so incredibly small (with an ionic radius of only 1.3·10−5 Ǻ) that it makes no contribution to the net bond length. The entire water molecule has a hard sphere diameter of 2.9 Ǻ, which is fairly typical for an oxygen anion. This means the unoccupied lone pairs are distended relative to the protonated lone pairs, extending out to roughly 1.9 Ǻ. The unequal distribution of charges introduces a dipole within the water molecule that facilitates electrostatic interactions with other molecules.

Catalytic Action of a Single Water Molecule in a Proton-Migration Reaction

2010 ◽  
Vol 122 (29) ◽  
pp. 5018-5021 ◽  
Author(s):  
Yoshiyuki Matsuda ◽  
Ayako Yamada ◽  
Ken-ichi Hanaue ◽  
Naohiko Mikami ◽  
Asuka Fujii
Keyword(s):  
Water Molecule ◽  
Catalytic Action ◽  
Proton Migration ◽  
Single Water Molecule
Sign in / Sign up

Export Citation Format

Share Document