Mean Value Ensemble Hubbard-<i>U</i> Correction for Spin-Crossover Molecules

Albavera-Mata, Angel; Trickey, S. B.; Hennig, Richard G.

doi:10.1021/acs.jpclett.2c03388

Cited by 7 publications

(17 citation statements)

References 81 publications

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“…That neglect leads to oversized U eff values for solids. More specifically, the methodology discussed in ref results in uncertainties of approximately ±2.3 kcal/mol (±100 meV) for the calculated U eff that, in turn, manifest themselves roughly as an accumulated 50 K uncertainty on T 1/2 . For PBE+ U eff in particular, the message in Figure is clear.…”

Section: Resultsmentioning

confidence: 99%

“…That compensation again raises the issue of uncertainties. The U eff values reported in ref were obtained only from the two closest molecules in a supercell. One expects, therefore, those values to be biased toward molecular properties in the sense that they neglect, entirely, crystal field effects upon spin crossover.…”

Section: Resultsmentioning

confidence: 99%

“…The set consists of 20 species , distributed as one Cr II , three each of Mn III , Mn II , and Fe III , and five each of Fe II and Co II ions. It is a subset of the test set used in ref , comprised of those complexes with a reported T 1/2 .…”

Section: Computational Detailsmentioning

confidence: 99%

“…Workflow used in ref for the calculation of the Hubbard- U eff value for each of the spin-crossover complexes. From the top, first is isolation of the bimolecular sample from a supercell, second is geometry relaxation for that sample, and third is determination of U eff using a linear response procedure …”

Section: Computational Detailsmentioning

confidence: 99%

“…In the setting of spin crossover, unfortunately those methods can give drastically inaccurate U values or fail to give any meaningful value at all . To address that, recently we introduced an effective Hubbard- U correction, U eff = U – J , determined from a spin-state built from a linearly mixed ensemble of the pure LS and HS states . Compared with the uncorrected density functional approximation, the methodology improves, significantly, the calculated ΔE HL values for a representative set of metal–organic molecules.…”

Section: Introductionmentioning

confidence: 99%

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

Albavera-Mata,

Hennig,

Trickey

2023

J. Phys. Chem. A

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Calculation of transition temperatures T 1/2 for thermally driven spin-crossover in condensed phases is challenging, even with sophisticated state-of-the-art density functional approximations. The first issue is the accuracy of the adiabatic crossover energy difference ΔE HL between the low- and high-spin states of the bistable metal–organic complexes. The other is the proper inclusion of entropic contributions to the Gibbs free energy from the electronic and vibrational degrees of freedom. We discuss the effects of treatments of both contributions upon the calculation of thermochemical properties for a set of 20 spin-crossover materials using a Hubbard-U correction obtained from a reference ensemble spin-state. The U values obtained from a simplest bimolecular representation may overcorrect, somewhat, the ΔE HL values, hence giving somewhat excessive reduction of the T 1/2 results with respect to their U = 0 values in the crystalline phase. We discuss the origins of the discrepancies by analyzing different sources of uncertainties. By use of a first-coordination-sphere approximation and the assumption that vibrational contributions from the outermost atoms in a metal–organic complex are similar in both low- and high-spin states, we achieve T 1/2 results with the low-cost, widely used PBE generalized gradient density functional approximation comparable to those from the more costly, more sophisticated r2SCAN meta-generalized gradient approximation. The procedure is promising for use in high-throughput materials screening, because it combines rather low computational effort requirements with freedom from user manipulation of parameters.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Computational Detailsmentioning

confidence: 99%

Section: Computational Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Albavera-Mata,

Hennig,

Trickey

2023

J. Phys. Chem. A

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Benchmarking Periodic Density Functional Theory Calculations for Spin-State Energies in Spin-Crossover Systems

Gómez-Coca,

Ruiz

2024

Inorg. Chem.

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Spin energetics is one of the biggest challenges associated with energy calculations for electronic structure methods. The energy differences of the spin states in spincrossover compounds are very small, making them one of the most difficult systems to calculate. Few methods provide accurate results for calculating these energy differences. In addition, studies have usually focused on calculating energetics of single molecules, while spin-crossover properties are usually experimentally studied in the solid phase. In this paper, we have used periodic boundary conditions employing methods based on density functional theory to calculate the high-and low-spin energy differences for a test case of 20 extended systems. Compounds with different metals and ligands have been selected, and the results indicate that a semiquantitative description of the energy differences can be obtained with the combination of geometry optimization using the PBE functional including many-body dispersion approach and the use of meta-GGA functionals, such as r 2 SCAN but especially KTBM24, for the energy calculation. Other hybrid functionals, such as TPSSh, give generally good results, but the calculation of the exact exchange with periodic boundary conditions involves a huge increase in computer time and computational resources. It makes the proposed nonhybrid functional approach (KTBM24//PBE+MB) a great advantage for the study of periodic systems.

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Artificial Neural Network-Based Density Functional Approach for Adiabatic Energy Differences in Transition Metal Complexes

de Mendonça,

Mariano,

Devijver

et al. 2023

J. Chem. Theory Comput.

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During the past decades, approximate Kohn−Sham density functional theory schemes have garnered many successes in computational chemistry and physics, yet the performance in the prediction of spin state energetics is often unsatisfactory. By means of a machine learning approach, an enhanced exchange and correlation functional is developed to describe adiabatic energy differences in transition metal complexes. The functional is based on the computationally efficient revision of the regularized, strongly constrained, and appropriately normed functional and improved by an artificial neural network correction trained over a small data set of electronic densities, atomization energies, and/or spin state energetics. The training process, performed using a bioinspired nongradient-based approach adapted for this work from the particle swarm optimization, is analyzed and discussed extensively. The resulting machine learned meta-generalized gradient approximation functional is shown to outperform most known density functionals in the prediction of adiabatic energy differences for a diverse set of transition metal complexes with varying local coordinations and metal choices.

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Mean Value Ensemble Hubbard-U Correction for Spin-Crossover Molecules

Cited by 7 publications

References 81 publications

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

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

Benchmarking Periodic Density Functional Theory Calculations for Spin-State Energies in Spin-Crossover Systems

Artificial Neural Network-Based Density Functional Approach for Adiabatic Energy Differences in Transition Metal Complexes

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