scholarly journals Nuclear inelastic scattering and density functional theory studies of a one-dimensional spin crossover [Fe(1,2,4-triazole)2(1,2,4-triazolato)](BF4) molecular chain

2017 ◽  
Vol 19 (29) ◽  
pp. 18880-18889 ◽  
Author(s):  
Kevin Jenni ◽  
Lena Scherthan ◽  
Isabelle Faus ◽  
Jennifer Marx ◽  
Cornelius Strohm ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Inelastic Scattering ◽  
Density Functional ◽  
Spin Crossover ◽  
Nuclear Inelastic Scattering ◽  
Spin States ◽  
Functional Theory ◽  
Vibrational Dynamics ◽  
One Dimensional ◽  
High Spin States

NIS experiments display the vibrational dynamics of the low- and high-spin states of the 1D spin crossover compound [Fe(trzH)2(trz)](BF4) (1).

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.

scholarly journals A Density Functional Theory Investigation of the Reaction of Water with Ce2O-

2020 ◽  
Author(s):  
Hassan Harb ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Function Theory ◽  
Practical Importance ◽  
Density Function Theory ◽  
Catalyst Design ◽  
Reaction Pathways ◽  
Spin States ◽  
Functional Theory ◽  
Energy Science

<div>Cerium suboxide clusters have been shown to react with water to yield H<sub>2</sub>. Since reactions of metal oxides with water are of great fundamental and practical importance in energy science, detailed study of this reaction can provide new key knowledge for future catalyst design. Using density function theory calculations, we identified and report complete reaction pathways for two spin-states of Ce<sub>2</sub>O<sup>–</sup> reacting with H<sub>2</sub>O. Additionally, examining the molecular orbitals of initial and final cerium oxide clusters, we found that metal d electrons facilitate the reduction of water. This work provides new understanding of this reaction and insights to the reactivity enhancements for cerium-doped surfaces.</div>

Pharmaceutical salts of emoxypine with dicarboxylic acids

2018 ◽  
Vol 74 (7) ◽  
pp. 797-806 ◽  
Author(s):  
Alex N. Manin ◽  
Alexander P. Voronin ◽  
Ksenia V. Drozd ◽  
Andrei V. Churakov ◽  
German L. Perlovich
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dicarboxylic Acids ◽  
Lattice Energy ◽  
State Density ◽  
Functional Theory ◽  
One Dimensional ◽  
Fusion Enthalpy ◽  
Pharmaceutical Salts ◽  
Salt Forms

New salt forms of the antioxidant drug emoxypine (EMX, 2-ethyl-6-methylpyridin-3-ol) with pharmaceutically acceptable maleic (Mlt), malonic (Mln) and adipic (Adp) acids were obtained {emoxypinium maleate, C8H12NO+·C4H3O4 −, [EMX+Mlt], emoxypinium malonate, C8H12NO+·C3H3O4 −, [EMX+Mln], and emoxypinium adipate, C8H12NO+·C6H9O4 −, [EMX+Adp]} and their crystal structures determined. The molecular packing in the three EMX salts was studied by means of solid-state density functional theory (DFT), followed by QTAIMC (quantum theory of atoms in molecules and crystals) analysis. It was found that the major contribution to the packing energy comes from pyridine–carboxylate and hydroxy–carboxylate heterosynthons forming infinite one-dimensional ribbons, with [EMX+Adp] additionally stabilized by hydrogen-bonded C(9) chains of Adp− ions. The melting processes of the [EMX+Mlt] (1:1), [EMX+Mln] (1:1) and [EMX+Adp] (1:1) salts were studied and the fusion enthalpy was found to increase with the increase of the calculated lattice energy. The dissolution process of the EMX salts in buffer (pH 7.4) was also studied. It was found that the formation of binary crystals of EMX with dicarboxylic acids increases the EMX solubility by more than 30 times compared to its pure form.

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