I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

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Conceptual density functional theory.

The electrophilic/nucleophilic character of a series of captodative (CD) ethylenes involved in polar cycloaddition reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The transition state structures for the electrophilic/nucleophilic interactions of two CD ethylenes toward a nucleophilically activated ethylene, 2-methylene-1,3-dioxolane, and an electrophilically activated ethylene, 1,1-dicyanoethyelene, have been studied, and their electronic structures have been characterized using both NBO and ELF methods. Analysis of the reactivity indexes of the CD ethylenes explains the reactivity of these species. While the electrophilicity of the molecules accounts for the reactivity toward nucleophiles, it is shown that a simple index chosen for the nucleophilicity, Ν, based on the HOMO energy is useful explaining the reactivity of these CD ethylenes toward electrophiles.

Understanding the reactivity of captodative ethylenes in polar cycloaddition reactions. A theoretical study.

Density functional theory (DFT) as a powerful tool for designing new organic corrosion inhibitors. Part 1: An overview

Easy processing and flexibility of polymer electrolytes make them very promising in developing all-solid-state lithium batteries. However, their low room-temperature conductivity and poor mechanical and thermal properties still hinder their applications. Here, we use Li6.75La3Zr1.75Ta0.25O12 (LLZTO) ceramics to trigger structural modification of poly(vinylidene fluoride) (PVDF) polymer electrolyte. By combining experiments and first-principle calculations, we find that La atom of LLZTO could complex with the N atom and C═O group of solvent molecules such as N,N-dimethylformamide along with electrons enriching at the N atom, which behaves like a Lewis base and induces the chemical dehydrofluorination of the PVDF skeleton. Partially modified PVDF chains activate the interactions between the PVDF matrix, lithium salt, and LLZTO fillers, hence leading to significantly improved performance of the flexible electrolyte membrane (e.g., a high ionic conductivity of about 5 × 10–4 S cm–1 at 25 °C, high mechanical s...

Synergistic Coupling between Li6.75La3Zr1.75Ta0.25O12 and Poly(vinylidene fluoride) Induces High Ionic Conductivity, Mechanical Strength, and Thermal Stability of Solid Composite Electrolytes

By introducing an electron bath that represents the chemical environment in which a chemical species is immersed, and by making use of the second-order Taylor series expansions of the energy as a function of the number of electrons in the intervals between N - 1 and N, and N and N + 1, we show that the electrodonating (omega-) and the electroaccepting (omega+) powers may be defined as omega-/+ = (mu-/+)2/2eta-/+, where mu-/+ are the chemical potentials and eta-/+ are the chemical hardnesses, in their corresponding intervals. Approximate expressions for omega- and omega+ in terms of the ionization potential I and the electron affinity A are established by assuming that eta- = eta+ = eta = mu+ - mu-. The functions omega-/+(r) = omega-/+f -/+(r), where f -/+(r) are the directional Fukui functions, derived from a functional Taylor series for the energy functional truncated at second order, represent the local electrodonating and electroaccepting powers.

Electrodonating and electroaccepting powers.

Electrochemical and XPS studies of decylamides of α-amino acids adsorption on carbon steel in acidic environment

Four molecules that have been proven to act as corrosion inhibitors of mild steel in acidic media are studied. The inhibitive efficiency of these molecules is explained by means of electronic structure calculations of the protonated species that seem to represent better the actual situation of the experimental conditions. By assuming that the interaction between the inhibitor and the metallic surface occurs through donation and back-donation, it is shown, with a simple charge transfer model, that the interaction energy is favored when hardness increases, in agreement with the experimentally observed inhibition efficiencies. A local analysis with Hirshfeld condensed Fukui functions, and local Fukui functions, provides further support to the donation and back-donation mechanism.

Quantum Chemical Study of the Inhibitive Properties of 2-Pyridyl-Azoles

In the present work, the molecular interactions of four amino acid compounds were simulated through the density functional theory (DFT) indexes to study their inhibitive properties. The prototype inhibitors previously synthesized 2-amino-N-decylacetamide (G), 2-amino-N-decylpropionamide (A), 2-amino-N-decyl-3-methylbutyramide (V), and 2-amino-N-decyl-3-(4-hydroxyphenyl)propionamide (T) were used to test the accuracy of this calculation. The generalized gradient approximation (GGA) was the ab initio approach used to optimize the ground state of the molecules. The simulation of molecular dynamics with force field (AMBER) was calculated to obtain the interaction energy between the metallic surface and the inhibitor molecules. A strong correlation of the global and local indexes with the inhibiting capacity was observed. The inhibitive properties of compounds on mild steel in an aqueous hydrochloric acid solution agreed well with those derived from the reactivity and selectivity indexes in gaseous phase.

Theoretical Study of a New Group of Corrosion Inhibitors

The Claisen rearrangement of allyl phenyl ether, allyl phenylamine, and allyl phenyl thioether, together with the family of H, CH3, OCH3, Cl, F, and CN, meta-substituted molecules, is studied withi...

A density functional study of the Claisen rearrangement of allyl aryl ether, allyl arylamine, allyl aryl thio ether, and a series of meta-substituted molecules through reactivity and selectivity profiles

The aggregation of proteins in the brain is one of the main features of neurodegenerative diseases. In Alzheimer's disease, the abnormal aggregation of Aβ-42 is due to intrinsic and extrinsic factors. The latter is due to variations in the environment, such as temperature, salt concentration, and pH. We evaluated the effect of protonation/deprotonation of residues that are part of trimeric and pentameric oligomers at pH 5, pH 6, and pH 7. Molecular dynamics simulation at 200 ns in the canonical ensemble was implemented. The results have revealed that histidine, glutamic acid, and aspartic acid residues showed a protonation/deprotonation effect in oligomers. The root mean square deviation analysis was used to analyze the structural stability at different pHs. We found an increase in hydrophobicity in the side chains of the trimer, while in the pentamer, the structural instability of a compact structure at pH 5 caused the hydrophobic core to open, revealing the hydrophobic region to the environment. At this point, we believe that conformational changes mediated by pH are essential in the aggregation of Aβ-42 oligomers.

Badhin Gómez

Papers

Electrochemical and XPS studies of decylamides of α-amino acids adsorption on carbon steel in acidic environment

Quantum Chemical Study of the Inhibitive Properties of 2-Pyridyl-Azoles

Theoretical Study of a New Group of Corrosion Inhibitors

A density functional study of the Claisen rearrangement of allyl aryl ether, allyl arylamine, allyl aryl thio ether, and a series of meta-substituted molecules through reactivity and selectivity profiles

Amyloid beta oligomers: how pH influences over trimer and pentamer structures?