Magnetic gaps in organic tri-radicals: From a simple model to accurate estimates

Barone, Vincenzo; Cacelli, Ivo; Ferretti, Alessandro; Prampolini, Giacomo

doi:10.1063/1.4977598

Cited by 6 publications

(7 citation statements)

References 85 publications

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“…Here, the three NBOs are almost degenerate and most of the low-lying states have heavily multiconfigurational wave functions. Accurate theoretical studies are available for the energy gap between the ground state and the energetically lowest doublet state. ,,− The doublet state is accessible with just a single SF operation on the high spin quartet state ( ); see the sketch in Figure a.…”

Section: Resultsmentioning

confidence: 99%

“… a Optimized geometry with UB3LYP/cc-pVDZ. b Geometry from ref , with UB3LYP/6-311G(d,p). c The energy gap for TMB – was obtained using 1SF-EA operation. All results with aug-cc-pVDZ basis set and natural orbitals truncated with a threshold of 0.0001. d CAS(3,3) for TMB, CAS(4,3) for TMB – , and CAS(2,2) for MX. e CASSCF(9,9)/6-31G(d,p) from ref . f DDCI/6-31G(d) using localized orbitals and complete virtual orbitals (fully variational) from ref . g CASPT2/6-31G(d,p) with CASSCF(9,9) orbitals from ref . h CASSCF(10,9)/ANO-L and CASPT2/ANO-L using the same CASSCF orbitals from ref . i State-averaged MS-CASPT2/ANO-L from ref . j CASSCF/6-31G(d) with CAS(8,8) from ref . k CASPT2/6-31G(d) with CASSCF orbitals with CAS(8,8) from ref . l EOM-SF-CCSD/6-31G(d) from ref . m Multireference second-order Møller–Plesset/aug-cc-pVTZ from ref . n LCCQMC/6-311++g(d,p) from ref . …”

Section: Resultsmentioning

confidence: 99%

“… f DDCI/6-31G(d) using localized orbitals and complete virtual orbitals (fully variational) from ref . …”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Spin-Flip Pair-Density Functional Theory: A Practical Approach To Treat Static and Dynamical Correlations in Large Molecules

Mayhall

2021

J. Chem. Theory Comput.

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We present a practical approach to treat static and dynamical correlation accurately in large multiconfigurational systems. The static correlation is taken into account by using the spin-flip approach, which is well-known for capturing static correlation accurately at low-computational expense. Unlike previous approaches to add dynamical correlation to spin-flip models which use perturbation theory or coupled-cluster theory, we explore the ability to use the on-top pair-density functional theory approaches recently developed by Gagliardi and co-workers (J. Comput. Theor. Chem., 2014, 10, 3669). External relaxations are performed in the spin-flip calculations through a restricted active space framework for which a truncation scheme for the orbitals used in the external excitation is presented. The performance of the approach is demonstrated by computing energy gaps between ground and excited states for diradicals, triradicals, and linear polyacene chains ranging from naphthalene to dodecacene. Accurate results are obtained using the new approach for these challenging open-shell molecular systems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Spin-Flip Pair-Density Functional Theory: A Practical Approach To Treat Static and Dynamical Correlations in Large Molecules

Mayhall

2021

J. Chem. Theory Comput.

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“…1,3,5,-Trimethylenebenzene ( TriMB on Figure ) is the basis of many high-spin polyradicals described in the literature and has a quartet ground state. , With few experiments available, it was only recently studied using matrix isolation spectrocopy . Theoretical computations based on CASSCF and CASPT2N found an adiabatic doublet-quartet energy splitting of 0.6–0.7 eV , that has been corroborated in a recent work based on the DDCI CAS(3,3) methodology …”

mentioning

confidence: 86%

Energy Gaps of Polyradicals from an Effective and Transferable Hamiltonian with through-Bond Interactions

Moreira

2017

J. Chem. Theory Comput.

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Current model Hamiltonians and ab initio many-body quantum treatments of π-conjugated polyradicals formed from hydrocarbons produce divergent results because of numerical complexity and large size of the basis-function set used. We propose an alternative, three-term Hamiltonian, to describe these various polyradicals that simplifies considerably the computational cost while providing a physical interpretation for all three terms and a high degree of model universality. The essential feature of this Hamiltonian is a term, not present in previous models, describing the three-sited through-bond interaction that governs the noninteracting spin-up and spin-down sectors. A computation of the lowest energy gaps and spin configurations for the smaller polyradicals demonstrates the efficacy of the model and its potential in applications in revealing electrical conductivity and ferromagnetism of the more complicated substituted polyradicals.

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“…Here, the three NBOs are nearly degenerate and most of the low-lying states have heavily multiconfigurational wavefunctions. Accurate theoretical studies are available for the energy gap between the ground state and the energetically lowest doublet state [83][84][85][86][87][88] . The doublet state is accesible with just a single spin-flip operation on the high spin quartet state (m s = 3 2 ), see the sketch in Figure 2(a).…”

Section: A All π-Polyradicalsmentioning

confidence: 99%

Spin-flip pair-density functional theory: A practical approach to treat static and dynamical correlations in large molecules

Mayhall¹

2021

Preprint

View full text Add to dashboard Cite

We present a practical approach to treat static and dynamical correlation accurately in large multi-configurational systems. The static correlation is accounted for using the spin-flip approach which is well known for capturing static correlation accurately at low-computational expense. Unlike previous approaches to add dynamical correlation to spin-flip models which use perturbation theory or coupled-cluster theory, we explore the ability to use the on-top pair-density functional theory approaches recently developed by Gagliardi and co-workers (JCTC, 10, 3669, 2014). External relaxations are carried out in the spin-flip calculations though a restricted active space framework for which a truncation scheme for the orbitals used in the external excitation is presented. The performance of the approach is demonstrated by computing energy gaps between ground and excited states for diradicals, triradicals and linear polyacene chains ranging from naphthalene to dodecacene. Accurate results are obtained using the new approach for these challenging open-shell molecular systems.

show abstract

Magnetic gaps in organic tri-radicals: From a simple model to accurate estimates

Cited by 6 publications

References 85 publications

Spin-Flip Pair-Density Functional Theory: A Practical Approach To Treat Static and Dynamical Correlations in Large Molecules

Spin-Flip Pair-Density Functional Theory: A Practical Approach To Treat Static and Dynamical Correlations in Large Molecules

Energy Gaps of Polyradicals from an Effective and Transferable Hamiltonian with through-Bond Interactions

Spin-flip pair-density functional theory: A practical approach to treat static and dynamical correlations in large molecules

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