scholarly journals Assessment of density functional approximations for calculation of exchange coupling constants in thiocyanato and cyanato double bridged binuclear Ni(II) complexes

2020 ◽  
pp. 71-71
Author(s):  
Matija Zlatar ◽  
Filip Vlahovic ◽  
Dragana Mitic ◽  
Mario Zlatovic ◽  
Maja Gruden
Keyword(s):  
Magnetic Properties ◽  
Exchange Coupling ◽  
Density Functional ◽  
Coupling Constants ◽  
Antiferromagnetic Coupling ◽  
Binuclear Complexes ◽  
Coupling Constant ◽  
Symmetry Approach ◽  
Experimental Values ◽  
Broken Symmetry Approach

In the present work, we examine the magnetic properties of 8 "endto-end" thiocyanato, and 3 "end-to-end" cyanato double bridged Ni(II) binuclear complexes. Thiocyanato complexes are weakly ferromagnetic. Cyanato bridged complexes exhibit weak antiferromagnetic coupling. Therefore, it is a challenge for computational chemistry to calculate the exchange coupling constant in these systems accurately. 17 different Density Functional Approximations with different flavors are used to find the method of choice to study magnetic properties in binuclear Ni(II) complexes within the Broken-Symmetry approach. It is found that M06-2X and PWPB95 performed the best compared to experimental values for the entire set of examined complexes. Furthermore, the magneto-structural correlation rationalizes the results.

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.

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