How Accurately Can We Describe Spin Crossover?
Abstract
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, T1/2. The difficulty lies in the intricate connection between the spin-crossover energy, which is a molecular spectroscopic property, and T1/2, a condensed phase property. Here we show how to obtain spin-crossover energies systematically by reverse engineering of experimental T1/2 data. The protocol is based upon fitting the range separation parameter, ω, in the hybrid LC-ωPBE density functional to reproduce the experimental T1/2 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 T1/2. 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.
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BibTeX
@misc{albaveramata2026accurately,
title = {{How Accurately Can We Describe Spin Crossover?}},
author = {Angel Albavera-Mata and Daniel Mejía-Rodríguez and Niranjan Govind and Ajay Panyala and Richard G. Hennig and S. B. Trickey},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15777},
eprint = {2609.15777},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15777},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - How Accurately Can We Describe Spin Crossover?
AU - Angel Albavera-Mata
AU - Daniel Mej{í}a-Rodr{í}guez
AU - Niranjan Govind
AU - Ajay Panyala
AU - Richard G. Hennig
AU - S. B. Trickey
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.15777
UR - https://arxiv.org/abs/2609.15777
AB - 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, T_1/2. The difficulty lies in the intricate connection between the spin-crossover energy, which is a molecular spectroscopic property, and T_1/2, a condensed phase property. Here we show how to obtain spin-crossover energies systematically by reverse engineering of experimental T_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 T_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 T_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.
ER -