A Range of Spin-Crossover TemperatureT1/2>300 K Results from Out-of-Sphere Anion Exchange in a Series of Ferrous Materials Based on the 4-(4-Imidazolylmethyl)-2-(2-imidazolylmethyl)imidazole (trim) Ligand, [Fe(trim)2]X2 (X=F, Cl, Br, I): Comparison of Experimental Results with Those Derived from Density Functional Theory Calculations

2006 ◽  
Vol 12 (28) ◽  
pp. 7421-7432 ◽  
Author(s):  
Gilles Lemercier ◽  
Nicolas Bréfuel ◽  
Sergiu Shova ◽  
Juliusz A. Wolny ◽  
Françoise Dahan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Anion Exchange ◽  
Density Functional ◽  
Spin Crossover ◽  
Density Functional Theory Calculations ◽  
Experimental Results ◽  
Functional Theory

Anticipating π-Bond Dispositions in Cyclic, Even, Classical Hydrocarbons

2011 ◽  
Vol 64 (3) ◽  
pp. 324 ◽  
Author(s):  
Richard F. Langler
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Experimental Results ◽  
New Technique ◽  
Structural Isomers ◽  
Functional Theory ◽  
Singlet States ◽  
Hückel Theory ◽  
A New Technique

A new technique, which employs π-bond placement coefficients, is presented. That technique, in conjunction with a few parameters that are readily available from traditional Hückel theory, permits one to systematically anticipate π-bond placements for optimized lowest-lying singlet states. One may then foresee the relative magnitudes of calculated ΔHf values for selected sets of structural isomers. Structural predictions are compared with parameterization method 3 (PM3) calculations, density functional theory calculations and experimental results. Reasonable expectations for the most stable structure narrow the choice of molecules that may then be scrutinized by more exact computations or by experiment.

From HCOOH to CO on Pd catalyst: theoretical study

2017 ◽  
Vol 95 (10) ◽  
pp. 1081-1084 ◽  
Author(s):  
Yingying Wang ◽  
Zijiao Chen
Keyword(s):  
Density Functional Theory ◽  
Formic Acid ◽  
Density Functional ◽  
Theoretical Study ◽  
Density Functional Theory Calculations ◽  
Experimental Results ◽  
Pd Catalyst ◽  
Co Poisoning ◽  
Functional Theory ◽  
Experimental Findings

The present theoretical and experimental results in the literature for formic acid (HCOOH) oxidation into CO on Pd(111) cannot rationalize the well-known, easy CO poisoning. The present study reexamines HCOOH oxidation on Pd(111) by performing density functional theory calculations. Upon a thorough search, we present a new adsorption configuration of HCOOH on Pd(111). From the calculated energy pathway, we proposed that CO arises from the reduction of the hydrogenation product CO2 and direct dehydration of formic acid during HCOOH oxidation on Pd(111), with latter step being energetically easier. The present theoretical study rationalizes the early experimental findings and provides insights into the deactivation problem of Pd catalyst in the process of HCOOH oxidation.

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.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

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