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oai:figshare.com:article/34018296 2026-09-28T19:09:25Z category_1 category_4 category_915 category_7 category_21 category_873 portal_63 item_type_6 month_year_09_2026

How Accurately Can We Describe Spin Crossover? Angel Albavera-Mata (14289786) Daniel Mejía-Rodríguez (5901137) Niranjan Govind (1277112) Ajay Panyala (17876361) Richard G. Hennig (1330377) S. B. Trickey (6083618) Biophysics Biochemistry Physical Sciences not elsewhere classified Medicine Biotechnology Chemical Sciences not elsewhere classified ωpbe density functional range separation parameter complicated physicochemical properties based upon fitting crossover energies systematically crossover energies due molecular spectroscopic property ± 50 k spin state energies excitation series upon describe spin crossover reference data set 2 </ sub crossover energy reference data phase property >< sub obtain spin extracted spin transition temperatures smaller molecules reverse engineering provide insights present results metal complexes intricate connection hybrid lc difficulty lies correlation functionals common exchange The complicated physicochemical properties of metal complexes that exhibit thermal spin crossover make it difficult for routine electronic structure calculations to yield an accurate transition temperature prediction, <i>T</i>_1/2. The difficulty lies in the intricate connection between the spin-crossover energy, which is a molecular spectroscopic property, and <i>T</i>_1/2, a condensed-phase property. Here we show how to obtain spin-crossover energies systematically by reverse engineering of experimental <i>T</i>_1/2 data. The protocol is based upon fitting the range separation parameter, ω, in the hybrid LC-ωPBE density functional to reproduce the experimental <i>T</i>_1/2 values for a series of metal complexes. We provide insights into the sources of variations of at least ±15 kJ mol^–1 found from common exchange and correlation functionals by comparing their performance against our reference data. By analysis of the sensitivity of transition temperatures to ±1% shifts in the range separation parameter, we determined a typical uncertainty of ±50 K for them, and a ±2 kJ mol^–1 uncertainty in the extracted spin-crossover energies due to ±1% variations of <i>T</i>_1/2. Lastly, we present results from the high-level, all-electron coupled cluster method for eight of the smaller molecules in the reference data set, and discuss the influence of the truncation of the excitation series upon the spin state energies. 2026-09-28T00:00:00Z Text Journal contribution 10.1021/acs.jctc.6c01104.s001 https://figshare.com/articles/journal_contribution/How_Accurately_Can_We_Describe_Spin_Crossover_/34018296 CC BY-NC 4.0