Spin-State Energetics of Fe Complexes from an Optimally Tuned Range-Separated Hybrid Functional

Area of Science:

• Quantum chemistry
• Computational materials science

Background:

• Predicting spin-state energetics and electronic configurations is crucial for understanding transition metal complexes.
• Optimally tuned range-separated hybrid (OT-RSH) functionals offer a promising approach for electronic structure calculations.

Purpose of the Study:

• To evaluate the performance of the OT-RSH functional for predicting ground-state electronic configuration and spin-state energetics.
• To investigate the influence of short-range exact exchange and range-separation parameters on these properties.

Main Methods:

• Investigated eight iron complexes, including four spin-crossover complexes and four smaller complexes.
• Compared OT-RSH results with reference data from other density functionals and ab initio calculations.

Main Results:

• Spin-state energetics are primarily determined by the percentage of short-range exact exchange.
• The fundamental gap is highly sensitive to the range-separation parameter.
• Accurate prediction of ground states in spin-crossover compounds necessitates reduced short-range exact exchange.

Conclusions:

• OT-RSH functional shows good performance for spin-state energetics but requires careful tuning of parameters for electronic structure.
• Static correlation plays a significant role in the accurate prediction of ground states for spin-crossover systems.