Intruder states in multireference perturbation theory: The ground state of manganese dimer

Camacho, Cristopher; Witek, Henryk A.; Yamamoto, Shunzo

doi:10.1002/jcc.21074

Cited by 41 publications

(45 citation statements)

References 47 publications

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“…Assignment of the ground state of neutral Mn 2 dimer is challenging and is still under debate. The lowest total energy state of the dimer was found to possess the spin multiplicity of 11 if computed using density functional theory methods, [49][50][51] whereas Hartree-Fock based studies [52][53][54][55][56][57] have predicted a singlet 1 Σ g + state to be the ground state of Mn 2 . The latter is in agreement with an early experimental ESR study which predicted a singlet antiferromagnetic state for the dimer.…”

Section: Calibration Of Computational Methodsmentioning

confidence: 99%

Photoelectron spectra and structure of the Mnn− anions (n = 2–16)

Gutsev

Weatherford

Ramachandran

et al. 2015

The Journal of Chemical Physics

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Photoelectron spectra of the Mnn(-) anion clusters (n = 2-16) are obtained by anion photoelectron spectroscopy. The electronic and geometrical structures of the anions are computed using density functional theory with generalized gradient approximation and a basis set of triple-ζ quality. The electronic and geometrical structures of the neutral Mnn clusters have also been computed to estimate the adiabatic electron affinities. The average absolute difference between the computed and experimental vertical detachment energies of an extra electron is about 0.2 eV. Beginning with n = 6, all lowest total energy states of the Mnn(-) anions are ferrimagnetic with the spin multiplicities which do not exceed 8. The computed ionization energies of the neutral Mnn clusters are in good agreement with previously obtained experimental data. According to the results of our computations, the binding energies of Mn atoms are nearly independent on the cluster charge for n > 6 and possess prominent peaks at Mn13 and Mn13(-) in the neutral and anionic series, respectively. The density of states obtained from the results of our computations for the Mnn(-) anion clusters show the metallic character of the anion electronic structures.

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Section: Calibration Of Computational Methodsmentioning

confidence: 99%

Photoelectron spectra and structure of the Mnn− anions (n = 2–16)

Gutsev

Weatherford

Ramachandran

et al. 2015

The Journal of Chemical Physics

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“…states that have a similar zeroth order energy as the reference state. In addition to causing discontinuities in PES generation [105], in one instance, the presence of intruder states was blamed for the prediction of the incorrect ground state for Sc 2 [106]. While it is possible in some cases to simply use a shifting procedure to remove these states, the quality of calculated results can strongly depend on what specific shifting procedure is used [105].…”

Section: Accounting For Dynamic Correlationmentioning

confidence: 99%

Ironing out the photochemical and spin-crossover behavior of Fe(II) coordination compounds with computational chemistry

Ashley

Jakubı́ková

2017

Coordination Chemistry Reviews

111

117

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Effective strategies for designing Fe(II) coordination complexes with specifically tailored spinstate energetics can lead to advances in many areas of inorganic and materials chemistry. These include, but are not limited to, rational development of novel spin crossover complexes, efficient chromophores for photosensitization of dye-sensitized solar cells, and multifunctional materials.As the spin-state ordering of transition metal complexes is strongly rooted in their electronic structures, computational chemistry has naturally played an important role in assisting experimental work in this area. Unfortunately, despite many advances, accurate determination of the spin-state energetics of Fe(II) complexes still poses a remarkable challenge for virtually all applicable forms of electronic structure theory due to being controlled by a delicate balancing between correlation and exchange effects. This review focuses on some of the more notable successes and failures of modern electronic structure theory in properly describing these systems in the absence of solid-state effects. The strengths and weaknesses of using traditional wavefunction based methods and density functional theory are considered, and illustrative examples are provided to demonstrate that the modern computational chemist should make use of experimental data whenever possible and expect to utilize a combination of methods to obtain the best results. The review closes by briefly surveying some of the many interesting combined computational and experimental studies of Fe(II) chemistry that have lead to greater fundamental insight and practical understanding of this challenging class of systems.

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“…Another aspect that is worth a careful inspection concerns the presence of intruder states in the CASPT2 treatment. Our recent work [27,28] shows that spectroscopic and molecular parameters computed with multi-reference perturbation theory using shift technique may heavily depend on the magnitude of the shift parameter in situations when the calculations are plagued by severe intruder states [29]. Taking into account all the issues raised here, we feel that there exists a need for careful inspection of the previous theoretical results and testing various assumptions made in the previous work in order to give a final interpretation of the experimentally observed optical spectrum of 2T.…”

Section: Introductionmentioning

confidence: 99%