Transition Temperature for Spin-Crossover Materials with the Mean Value Ensemble Hubbard-U Correction

Area of Science:

• Computational Chemistry
• Materials Science
• Solid-State Physics

Background:

• Accurate calculation of spin-crossover (SCO) transition temperatures (T1/2) in condensed phases is computationally challenging.
• Accurate adiabatic crossover energy difference (ΔE_HL) and entropic contributions are critical for predicting SCO behavior.
• Existing density functional approximations (DFAs) struggle to balance accuracy and computational cost for SCO materials.

Purpose of the Study:

• To investigate the impact of Hubbard-U corrections and entropic contributions on SCO thermochemical properties.
• To develop a computationally efficient and accurate method for calculating T1/2 for SCO materials.
• To enable high-throughput screening of SCO materials by combining low computational cost with reliable predictions.

Main Methods:

• Employed a Hubbard-U correction derived from a reference ensemble spin-state for 20 SCO materials.
• Utilized a first-coordination-sphere approximation and assumed similar vibrational contributions from outer atoms.
• Compared the performance of the PBE generalized gradient DFA with the r2SCAN meta-generalized gradient DFA.

Main Results:

• The Hubbard-U correction, particularly from simple representations, can overcorrect ΔE_HL, leading to reduced T1/2 values.
• The proposed method using PBE-DFA achieves T1/2 results comparable to the more computationally expensive r2SCAN DFA.
• The simplified approach effectively captures essential thermochemical properties for SCO materials.

Conclusions:

• A computationally efficient approach combining PBE-DFA with specific approximations and Hubbard-U corrections enables accurate T1/2 prediction.
• This method offers a promising pathway for high-throughput computational screening of spin-crossover materials.
• The findings reduce the reliance on computationally intensive methods for SCO material characterization.