Chemical bond formation showing a transition from physisorption to chemisorption

Surface molecules can transition from physisorption through weak van der Waals forces to a strongly bound chemisorption state by overcoming an energy barrier. We show that a carbon monoxide (CO) molecule adsorbed to the tip of an atomic force microscope enables a controlled observation of bond formation, including its potential transition from physisorption to chemisorption. During imaging of copper (Cu) and iron (Fe) adatoms on a Cu(111) surface, the CO was not chemically inert but transited through a physisorbed local energy minimum into a chemisorbed global minimum, and an energy barrier was seen for the Fe adatom. Density functional theory reveals that the transition occurs through a hybridization of the electronic states of the CO molecule mainly with s-, pz-, and dz2-type states of the Fe and Cu adatoms, leading to chemical bonding.

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Research Optical Characteristics of H2S Molecule Adsorption on Agn (n=2,4,6) Clusters

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.321-324.499 ◽

2013 ◽

Vol 321-324 ◽

pp. 499-502

Author(s):

Hong Zhou ◽

Jun Feng Wang ◽

Jun Qing Wen ◽

Wei Bin Cheng ◽

Jun Fei Wang

Keyword(s):

Density Functional Theory ◽

Infrared Spectrum ◽

Density Functional ◽

Global Minimum ◽

Electronic States ◽

Binding Energies ◽

Optical Characteristics ◽

Functional Theory ◽

Calculation Results ◽

Planar Geometries

Density-functional theory has been used to calculate the energetically global-minimum geometries and electronic states of AgnH2S (n=2, 4, 6) clusters. The lowest-energy structures of Ag2, Ag4, Ag6, Ag2H2S, Ag4H2S and Ag6H2S clusters were obtained, respectively. The calculation results show that the lowest-energy structures of Ag2, Ag4and Ag6clusters are planar geometries. The binding energies of Agn(n=2, 4, 6) clusters are gradually increasing in our calculations. Compare the infrared spectrum peaks of Ag4cluster with that of Ag6cluster, which show that the peaks shift to shortwave. After adsorption, we found that the peaks shift to shortwave by comparison.

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Density Functional Study of H2S Adsorption on Small Agn (n = 1–5)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.47 ◽

2013 ◽

Vol 634-638 ◽

pp. 47-51 ◽

Cited By ~ 1

Author(s):

Jun Qing Wen ◽

A Ping Yang ◽

Guo Xiang Chen ◽

Chen Jun Zhang

Keyword(s):

Density Functional Theory ◽

Binding Energy ◽

Density Functional ◽

Global Minimum ◽

Electronic States ◽

Functional Study ◽

Functional Theory ◽

Energy Gaps ◽

Single Fold ◽

Homo And Lumo

The global-minimum geometries and electronic states of AgnH2S (n=1-5) clusters have been calculated using density-functional theory. Our calculations predicate that the stable geometries of AgnH2S clusters can be got by directly adding the H2S molecule on different site of Agn clusters, Agn (n=1-5) clusters would like to bond with sulfur atom and the H2S molecule is partial to hold the top location and single fold coordination site in the clusters. After adsorption, the structures of Agn clusters and H2S molecule keep the original structures and are only distorted slightly. The averaged binding energy reveals that adsorption of H2S molecule can strengthen the stabilities of AgnH2S clusters. The second difference in energy and the energy gaps between the HOMO and LUMO of Agn and AgnH2S have been studied.

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Density functional theory modeling of C–Au chemical bond formation in gold implanted polyethylene

Physical Chemistry Chemical Physics ◽

10.1039/c7cp05637k ◽

2017 ◽

Vol 19 (42) ◽

pp. 28897-28906 ◽

Cited By ~ 3

Author(s):

Andrej Antušek ◽

Martin Blaško ◽

Miroslav Urban ◽

Pavol Noga ◽

Danilo Kisić ◽

...

Keyword(s):

Density Functional Theory ◽

Ion Implantation ◽

Chemical Bond ◽

Density Functional ◽

Bond Formation ◽

Theoretical Chemistry ◽

Functional Theory ◽

Chemical Bond Formation ◽

Gold Ion

We have studied processes of gold ion implantation in polyethylene (PE) by theoretical chemistry methods.

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Study of Modification Mechanism of Ultrafine Silica Modified by PAMAM

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.217-219.252 ◽

2012 ◽

Vol 217-219 ◽

pp. 252-255

Author(s):

Jin Tao

Keyword(s):

Density Functional Theory ◽

Silicon Dioxide ◽

Gas Phase ◽

Density Functional ◽

Bond Formation ◽

Pamam Dendrimers ◽

Functional Theory ◽

Chemical Bond Formation ◽

Ultrafine Silica ◽

Site Types

Ultrafine silicon dioxide were modified by -NH2-teminated poly(amido-amine) (PAMAM) dendrimers to improve their dispersibility in the coatings. The modification mechanism was studied through density functional theory (DFT) in the gas phase. Virous initial configurations of ion bound to PAMAM were established to investigate the structures and the energetics of the complexes. Two stable conformers are found: types A ( is bound to the amine site) and C ( is bound to the amide site). Types A and C indicate the chemical bond formation of Si-N and Si-O, respectively.

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DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633618500505 ◽

2018 ◽

Vol 17 (08) ◽

pp. 1850050 ◽

Cited By ~ 1

Author(s):

Qiuhan Luo ◽

Gang Li ◽

Junping Xiao ◽

Chunhui Yin ◽

Yahui He ◽

...

Keyword(s):

Free Energy ◽

Water Molecule ◽

Carbonyl Group ◽

Energy Barrier ◽

Density Functional ◽

Free Energy Barrier ◽

Functional Theory ◽

Metsulfuron Methyl ◽

Catalytic Role ◽

Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

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First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633615500200 ◽

2015 ◽

Vol 14 (03) ◽

pp. 1550020 ◽

Cited By ~ 3

Author(s):

Yuan Yuan ◽

Wei Hu ◽

Xuhui Chi ◽

Cuihua Li ◽

Dayong Gui ◽

...

Keyword(s):

Diethyl Ether ◽

Energy Barrier ◽

Density Functional ◽

Oxidation Process ◽

Oxidation Mechanism ◽

High Energy ◽

First Principle ◽

Functional Theory ◽

The Third ◽

High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

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STRUCTURES, ABSORPTION SPECTRA, AND ELECTRONIC PROPERTIES OF POLYFLUORENE AND ITS DERIVATIVES: A THEORETICAL STUDY

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633606002520 ◽

2006 ◽

Vol 05 (03) ◽

pp. 595-608 ◽

Cited By ~ 13

Author(s):

KRIENGSAK SRIWICHITKAMOL ◽

SONGWUT SURAMITR ◽

POTJAMAN POOLMEE ◽

SUPA HANNONGBUA

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Energy Gap ◽

Level Energy ◽

Excitation Energies ◽

Lumo Energy ◽

Functional Theory ◽

Local Energy Minimum ◽

Pi Systems ◽

Homo Lumo

The structural and energetic properties of polyfluorene and its derivatives were investigated, using quantum chemical calculations. Conformational analysis of bifluorene was performed by using ab initio (HF/6-31G* and MP2/6-31G*) and density functional theory (B3LYP/6-31G*) calculations. The results showed that the local energy minimum of bifluorene lies between the coplanar and perpendicular conformation, and the B3LYP/6-31G* calculations led to the overestimation of the stability of the planar pi systems. The HOMO-LUMO energy differences of fluorene oligomers and its derivatives — 9,9-dihexylfluorene (DHPF), 9,9-dioctylfluorene (PFO), and bis(2-ethylhexyl)fluorene (BEHPF) — were calculated at the B3LYP/6-31G* level. Energy gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO energy differences and the lowest excitation energies to infinite chain length. The lowest excitation energies and the maximum absorption wavelength of polyfluorene were also performed, employing the time-dependent density functional theory (TDDFT) and ZINDO methods. The extrapolations, based on TDDFT and ZINDO calculations, agree well with experimental results. These theoretical methods can be useful for the design of new polymeric structures with a reducing energy gap.

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Effects of Hydroxyl and Carboxyl Functional Groups on Calcite Surface Wettability Using Atomic Force Microscopy and Density Functional Theory

ACS Earth and Space Chemistry ◽

10.1021/acsearthspacechem.1c00240 ◽

2021 ◽

Author(s):

Sooyeon Kim ◽

Maria C. Marcano ◽

Udo Becker

Keyword(s):

Density Functional Theory ◽

Atomic Force Microscopy ◽

Functional Groups ◽

Density Functional ◽

Surface Wettability ◽

Functional Theory ◽

Force Microscopy ◽

Atomic Force

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Prediction of Beryllium Clusters from First Principles: Be17 as a Promising New Material for Water Splitting

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02513a ◽

2021 ◽

Author(s):

Behnaz Abyaz ◽

Zabiollah Mahdavifar ◽

Georg Schreckenbach ◽

Yang Gao

Keyword(s):

Density Functional Theory ◽

Dft Calculations ◽

Water Splitting ◽

First Principles ◽

Density Functional ◽

Global Minimum ◽

Functional Theory ◽

New Material ◽

Universal Structure

Evolutionary searches using the USPEX method (Universal Structure Predictor: Evolutionary Xtallography) combined with density functional theory (DFT) calculations were performed to obtain the global minimum structures of beryllium (Ben, n=3-25)...

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