The Li-adsorbed C(100)-(1x1):O Diamond Surface

2011 ◽  
Vol 1282 ◽  
Author(s):  
Kane M. O’Donnell ◽  
Tomas L. Martin ◽  
Neil A. Fox ◽  
David Cherns
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Alkali Metals ◽  
Diamond Surface ◽  
Large Shift ◽  
Functional Theory ◽  
Vacuum Microelectronic ◽  
Monolayer Coverage

ABSTRACTThis paper presents density functional theory results for the Li-adsorbed C(100)-(1x1):O system. Previously it has been shown that at a single monolayer coverage, the binding energy for Li on oxygenated C(100) diamond is substantially higher than that of heavier alkali metals, while at the same time, the presence of the lithium generates a large shift in the diamond workfunction. The system is therefore promising for electronics applications involving diamond. Here, further calculations are presented showing that additional Li atoms above 1ML coverage are far less strongly bound, suggesting the 1ML surface is the most useful for vacuum microelectronic applications.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

scholarly journals Substitution Effects on the Optoelectronic Properties of Coumarin Derivatives

2019 ◽  
Vol 10 (1) ◽  
pp. 144
Author(s):  
Amit Kumar ◽  
Roberto Baccoli ◽  
Antonella Fais ◽  
Alberto Cincotti ◽  
Luca Pilia ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Molecular Orbital ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Exciton Binding Energy ◽  
Basis Set ◽  
Substitution Effects ◽  
Coumarin Derivatives ◽  
Functional Theory

Coumarin derivatives have gathered major attention largely due to their versatile utility in a wide range of applications. In this framework, we report a comparative computational investigation on the optoelectronic properties of 3-phenylcoumarin and 3-heteroarylcoumarin derivatives established as enzyme inhibitors. Specifically, we concentrate on the variation in the optoelectronic characteristics for the hydroxyl group substitutions within the coumarin moiety. In order to realize our aims, all-electron density functional theory and time dependent density functional theory calculations were performed with a localized Gaussian basis-set matched with a hybrid exchange–correlation functionals. Molecular properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, vertical ionization (IEV) and electron affinity energies, absorption spectra, quasi-particle gap, and exciton binding energy values are examined. Furthermore, the influence of solvent on the optical properties of the molecules is considered. We found a good agreement between the experimental (8.72 eV) and calculated (8.71 eV) IEV energy values for coumarin. The computed exciton binding energy of the investigated molecules indicated their potential optoelectronics application.

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

2013 ◽  
Vol 634-638 ◽  
pp. 47-51 ◽  
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.

scholarly journals Crossover from metal to insulator in dense lithium-rich compound CLi4

2016 ◽  
Vol 113 (9) ◽  
pp. 2366-2369 ◽  
Author(s):  
Xilian Jin ◽  
Xiao-Jia Chen ◽  
Tian Cui ◽  
Ho-kwang Mao ◽  
Huadi Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Fermi Surface ◽  
Density Functional ◽  
Alkali Metals ◽  
Alkaline Earth ◽  
Density Functional Theory Calculations ◽  
Alkaline Earth Metals ◽  
Functional Theory ◽  
Surface Filling

At room environment, all materials can be classified as insulators or metals or in-between semiconductors, by judging whether they are capable of conducting the flow of electrons. One can expect an insulator to convert into a metal and to remain in this state upon further compression, i.e., pressure-induced metallization. Some exceptions were reported recently in elementary metals such as all of the alkali metals and heavy alkaline earth metals (Ca, Sr, and Ba). Here we show that a compound of CLi4 becomes progressively less conductive and eventually insulating upon compression based on ab initio density-functional theory calculations. An unusual path with pressure is found for the phase transition from metal to semimetal, to semiconductor, and eventually to insulator. The Fermi surface filling parameter is used to describe such an antimetallization process.

Diffusion of Fluorine-Silicon Interstitial Complex in Crystalline Silicon

2005 ◽  
Vol 864 ◽  
Author(s):  
Scott A. Harrison ◽  
Thomas F. Edgar ◽  
Gyeong S. Hwang
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Charge State ◽  
First Principles ◽  
Density Functional ◽  
Positive Charge ◽  
Crystalline Silicon ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
And Diffusion

AbstractBased on first principles density functional theory calculations, we identify the structure and diffusion pathway for a fluorine-silicon interstitial complex (F-Sii). We find the F-Sii complex to be most stable in the singly positive charge state at all Fermi leVels. At mid-gap, the complex is found to have a binding energy of 1.08 eV relative to bond-centered F+ and (110)-split Sii. We find the F-Sii complex has an overall migration barrier of 0.76 eV, which suggests that this complex may play an important role in fluorine diffusion. Our results should lead to more accurate models that describe the behavior of fluorine co-implants crystalline silicon.

scholarly journals Graphite as A Hydrogen Storage in Fuel Cell System: Computational Material Study for Renewable Energy

2017 ◽  
Vol 17 (2) ◽  
pp. 103
Author(s):  
Rahmat Gunawan ◽  
Cynthia Linaya Radiman ◽  
Muhamad Abdulkadir Martoprawiro ◽  
Hermawan K. Dipojono
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Storage ◽  
Density Functional ◽  
Alkali Metals ◽  
Correlation Energy ◽  
Atomic Orbital ◽  
Hydrogen Gas ◽  
Basis Set ◽  
Functional Theory ◽  
Orbital Contribution

The Hydrogen storage based-graphite materials have been investigated theoretically via Density Functional Theory (DFT) approach. The native graphite was compared to the modified graphite, namely the intercalation graphite (GICs, graphite intercalated compounds). Here the GICs was intercalated by alkali metals (Li, Na and K). The electronic structures, energetics and atomic orbital contributions of hydrogen-graphite system, GICs, and hydrogen-GICs were studied by calculation approach of gradient corrected PBE (Perdew-Burke-Ernzerhof) for recovery of exchange-correlation energy. The calculation was supported by using basis set of the plane waves whereas the computation of electron-core by using Ultrasoft Vanderbilt pseudopotential. The computational calculation provides four main studies i.e. molecular geometry relaxation, determination of electronic bands structure of energy, energy state density (DOS) and atomic orbital contribution by charge density differences.Keywords: Density Functional Theory, hydrogen gas, graphite intercalated material

scholarly journals Electronic And Nonlinear Optical Features of Inorganic Ga12N12 Nanocage Decorated With Alkali Metals (Li, Na and K)

2021 ◽  
Author(s):  
Azadeh Jamshidi ◽  
Zeinab Biglari
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Alkali Metals ◽  
Nonlinear Optical ◽  
Interaction Energies ◽  
First Hyperpolarizability ◽  
Negative Interaction ◽  
Functional Theory ◽  
Nlo Properties ◽  
Homo Lumo

Abstract The effect of alkali metals (Li, Na and K) interaction on the nonlinear optical response (NLO) of Ga12N12 nanocage has been performed using density functional theory (DFT) calculations. The results show that the exo-M@Ga12N12 structures are energetically favorable with negative interaction energies in the range of ‒1.50 to ‒2.28 eV. The electronic properties of decorated structures are strongly sensitive to interaction with the alkali metals. The HOMO-LUMO gap of Ga12N12 is reduced by about 70% due to the decoration with alkali metals. It is obtained that the adsorption of alkali metals over the tetragonal ring of Ga12N12 nanocage remarkably enhances the first hyperpolarizability up to 6.5×104 au. The results display that decorating Ga12N12 nanocage with alkali metals can be introduced it as a novel inorganic nanomaterial with significant NLO properties.

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