Analysis of the Singlet–Triplet Splitting Computed by the Density Functional Theory–Broken-Symmetry Method: Is It an Exchange Coupling Constant?

2011 ◽  
Vol 50 (12) ◽  
pp. 5577-5586 ◽  
Author(s):  
Nicolas Onofrio ◽  
Jean-Marie Mouesca
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Broken Symmetry ◽  
Coupling Constant ◽  
Functional Theory ◽  
Triplet Splitting ◽  
Exchange Coupling Constant ◽  
The Density Functional Theory ◽  
Symmetry Method

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

2019 ◽  
Author(s):  
Xianghai Sheng ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Spin Crossover ◽  
Coupling Constants ◽  
Spin Projection ◽  
Coupling Constant ◽  
Projection Model ◽  
Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

2019 ◽  
Author(s):  
Lee Thompson ◽  
Hrant Hratchian ◽  
Xianghai Sheng
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Spin Crossover ◽  
Coupling Constants ◽  
Spin Projection ◽  
Coupling Constant ◽  
Projection Model ◽  
Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

Exchange-Correlation Energy Densities and Response Potentials: Connection Between Two Definitions and Analytical Model for the Strong-Coupling Limit of a Stretched Bond

2019 ◽  
Author(s):  
S. Giarrusso ◽  
Paola Gori-Giorgi
Keyword(s):  
Density Functional Theory ◽  
Strong Coupling ◽  
Density Functional ◽  
Correlation Energy ◽  
Order Term ◽  
Strong Coupling Limit ◽  
Local Form ◽  
Coupling Constant ◽  
Functional Theory ◽  
Exchange Correlation

We analyze in depth two widely used definitions (from the theory of conditional probablity amplitudes and from the adiabatic connection formalism) of the exchange-correlation energy density and of the response potential of Kohn-Sham density functional theory. We introduce a local form of the coupling-constant-dependent Hohenberg-Kohn functional, showing that the difference between the two definitions is due to a corresponding local first-order term in the coupling constant, which disappears globally (when integrated over all space), but not locally. We also design an analytic representation for the response potential in the strong-coupling limit of density functional theory for a model single stretched bond.<br>

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

scholarly journals Study on the interaction between catechin and cholesterol by the density functional theory

2020 ◽  
Vol 18 (1) ◽  
pp. 357-368
Author(s):  
Kaiwen Zheng ◽  
Kai Guo ◽  
Jing Xu ◽  
Wei Liu ◽  
Junlang Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Micelle Formation ◽  
Aromatic Rings ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractCatechin – a natural polyphenol substance – has excellent antioxidant properties for the treatment of diseases, especially for cholesterol lowering. Catechin can reduce cholesterol content in micelles by forming insoluble precipitation with cholesterol, thereby reducing the absorption of cholesterol in the intestine. In this study, to better understand the molecular mechanism of catechin and cholesterol, we studied the interaction between typical catechins and cholesterol by the density functional theory. Results show that the adsorption energies between the four catechins and cholesterol are obviously stronger than that of cholesterol themselves, indicating that catechin has an advantage in reducing cholesterol micelle formation. Moreover, it is found that the molecular interactions of the complexes are mainly due to charge transfer of the aromatic rings of the catechins as well as the hydrogen bond interactions. Unlike the intuitive understanding of a complex formed by hydrogen bond interaction, which is positively correlated with the number of hydrogen bonds, the most stable complexes (epicatechin–cholesterol or epigallocatechin–cholesterol) have only one but stronger hydrogen bond, due to charge transfer of the aromatic rings of catechins.

A trinuclear chromium(III) chlorocarbyne

2021 ◽  
Author(s):  
Takashi Kurogi ◽  
Keiichi Irifune ◽  
Takahiro Enoki ◽  
Kazuhiko Takai
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Terminal Alkynes ◽  
Functional Theory ◽  
The Density Functional Theory

Reduction of CCl4 by CrCl2 in THF afforded a trinuclear chromium(III) carbyne [CrCl(thf)2)]3(μ3-CCl)(μ-Cl)3. The chlorocarbyne complex reacted with aldehydes to afford chloroallylic alcohols and terminal alkynes. The density functional theory...

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