The one-electron self-interaction error in 74 density functional approximations: a case study on hydrogenic mono- and dinuclear systems

2020 ◽  
Vol 22 (28) ◽  
pp. 15805-15830 ◽  
Author(s):  
Dale R. Lonsdale ◽  
Lars Goerigk
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Model Systems ◽  
Electron Model ◽  
Functional Theory ◽  
The One

The one-electron self-interaction error (SIE) is analysed for 74 Density Functional Theory (DFT) approximations in a series of novel one-electron model systems revealing new aspects of the SIE that should be considered in future DFT developments.

Developing orbital-free quantum crystallography: the local potentials and associated partial charge densities

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Vladimir Tsirelson ◽  
Adam Stash
Keyword(s):  
Density Functional Theory ◽  
Electron Density ◽  
Density Functional ◽  
Electronic Energy ◽  
Physical Content ◽  
Functional Theory ◽  
Orbital Free ◽  
The One ◽  
Physical And Chemical ◽  
Quantum Crystallography

This work extends the orbital-free density functional theory to the field of quantum crystallography. The total electronic energy is decomposed into electrostatic, exchange, Weizsacker and Pauli components on the basis of physically grounded arguments. Then, the one-electron Euler equation is re-written through corresponding potentials, which have clear physical and chemical meaning. Partial electron densities related with these potentials by the Poisson equation are also defined. All these functions were analyzed from viewpoint of their physical content and limits of applicability. Then, they were expressed in terms of experimental electron density and its derivatives using the orbital-free density functional theory approximations, and applied to the study of chemical bonding in a heteromolecular crystal of ammonium hydrooxalate oxalic acid dihydrate. It is demonstrated that this approach allows the electron density to be decomposed into physically meaningful components associated with electrostatics, exchange, and spin-independent wave properties of electrons or with their combinations in a crystal. Therefore, the bonding information about a crystal that was previously unavailable for X-ray diffraction analysis can be now obtained.

scholarly journals Integrating Density Functional Theory Modeling with Experimental Data to Understand and Predict Sorption Reactions: Exchange of Salicylate for Phosphate on Goethite

Soil Systems ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 27 ◽  
Author(s):  
James D. Kubicki ◽  
Tsutomu Ohno
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Mineral Water ◽  
Surface Complexes ◽  
Functional Theory ◽  
Complex Models ◽  
Mechanical Approach ◽  
Plant Exudates ◽  
Quantum Mechanical Approach

Density functional theory (DFT) calculations are a quantum mechanical approach that can be used to model chemical reactions on an atomistic scale. DFT provides predictions on structures, thermodynamics, spectroscopic parameters and kinetics that can be compared against experimentally determined data. This paper is a primer on the basics of utilizing DFT for applications in mineral-water interfaces. In our case-study, we use DFT to model the surface complexes of phosphate and salicylate adsorbed onto the (101) and (210) surfaces of α-FeOOH (goethite), as an example of combining DFT and experiment. These three components are important in the phosphorus-organic matter interactions in soils, and by comparing the energies of the two surface complexes, the exchange energy of salicylate for phosphate onto goethite can be estimated. The structures of the surface complexes are predicted and the resulting vibrational frequencies calculated based on these structures are compared to previous observations. Upon verification of reasonable surface complex models, the potential energy of exchanging salicylate for phosphate is calculated and shown to be significantly exothermic. This model result is consistent with observations of plant exudates, such as salicylate freeing adsorbed phosphate in soils under P-limited conditions.

Experimental and Theoretical Study of the First Vanadocene(IV) Complexes of α-Amino Acids Prepared from Vanadocene Dichloride

2004 ◽  
Vol 69 (4) ◽  
pp. 811-821 ◽  
Author(s):  
Jaromír Vinklárek ◽  
Hana Paláčková ◽  
Jan Honzíček
Keyword(s):  
Amino Acids ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Model Systems ◽  
Amino Groups ◽  
Aqueous Methanol ◽  
Functional Theory ◽  
Elemental Analyses ◽  
Vanadocene Dichloride

The first bioinorganic vanadocene(IV) complexes of α-amino acids ([Cp2V(aa)]Cl, Cp = η5-C5H5, aa = glycine, L-alanine, L-valine) were prepared by reaction of vanadocene dichloride ([Cp2VCl2]) and α-amino acids in aqueous methanol. Analogous cationic complexes with PF6- counterions were obtained by metathetical reactions of the chloride precursors with KPF6. These compounds are of great interest as model systems for the vanadocene moiety binding to proteins. All complexes have been characterized by elemental analyses and IR, Raman and EPR spectroscopies. On the basis of EPR spectra, a chelate in all the studied complexes was proposed, formed by the carboxylato and amino groups. This structure has also been confirmed by density functional theory (DFT) calculations.

scholarly journals Density functional theory (DFT) calculations of conformational energies and interconversion pathways in 1,2,7-thiadiazepane

2011 ◽  
Vol 76 (3) ◽  
pp. 395-406 ◽  
Author(s):  
Mina Haghdadi ◽  
Nahid Farokhi
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Activation Barrier ◽  
Stable Conformer ◽  
Functional Theory ◽  
Conformational Interconversion ◽  
Interconversion Barrier ◽  
The One ◽  
Twist Boat

The molecular structure and conformational analysis of 1,2,7-thiadiazapane conformers were investigated by density functional theory (DFT) calculations at the B3LYP/cc-pVDZ level of theory. Four twist-chair (TC), six twist-boat (TB), two boat (B), two chair (C) and four twist (T) conformers were identified as minima and transition states for 1,2,7-thiadiazepane. The TC1 conformer is the most stable conformer and the twist-chair conformers are predicted to be lower in energy than their corresponding boat and chair conformations. DFT predicts a small barrier to pseudo-rotation and a remarkable activation barrier for the conformational interconversion of the twist-chair conformers to their corresponding boat conformers. The simplest conformational process and the one with the lowest barrier is the degenerate interconversion of the twist-chair 3 (TC3) conformation with itself via the CS symmetric chair (C2) transition state. The calculated strain energy barrier for this process is 2.41 kJ mol-1. The highest conformational interconversion barrier is between TC2 and twistboat 3 (TB3) forms, which was found to be 75.62 kJ mol-1.

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