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Patra R, Das M. Designing an Efficient Singlet Fission Material with B-N Substitution in Pyrene: A Model Exact Study. J Phys Chem A 2024. [PMID: 39167053 DOI: 10.1021/acs.jpca.4c03346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
The electronic structure of boron (B)-nitrogen (N)-substituted pyrene molecules is the center of attraction in designing an efficient intermolecular singlet fission (x-SF) material. Thermodynamic energy criteria required for x-SF are obtained by captodative substitution with B and N in pristine pyrene to increase the lowest singlet-triplet energy gap. We computed low-lying excited states of BN-embedded pyrene molecules by exactly solving the Pariser-Parr-Pople (PPP) model Hamiltonian and compared these results with the TDDFT and EOM-CCSD values. Exact diagonalization of the PPP model Hamiltonian suggests that pristine pyrene, which is endothermic for x-SF, becomes isoergic with certain (BN)2 substitution. The low-lying excited state energies calculated using the model Hamiltonian match very well with experimental values over EOM-CCSD and TDDFT. Moreover, the low value of the spin-orbit coupling constant calculated for BN-substituted pyrene strengthens its applicability as an SF material.
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Affiliation(s)
- Ramen Patra
- Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER), Kolkata, Mohanpur 741246, India
| | - Mousumi Das
- Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER), Kolkata, Mohanpur 741246, India
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2
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Drosou M, Bhattacharjee S, Pantazis DA. Combined Multireference-Multiscale Approach to the Description of Photosynthetic Reaction Centers. J Chem Theory Comput 2024; 20. [PMID: 39116215 PMCID: PMC11360140 DOI: 10.1021/acs.jctc.4c00578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/02/2024] [Accepted: 07/12/2024] [Indexed: 08/10/2024]
Abstract
A first-principles description of the primary photochemical processes that drive photosynthesis and sustain life on our planet remains one of the grand challenges of modern science. Recent research established that explicit incorporation of protein electrostatics in excited-state calculations of photosynthetic pigments, achieved for example with quantum-mechanics/molecular-mechanics (QM/MM) approaches, is essential for a meaningful description of the properties and function of pigment-protein complexes. Although time-dependent density functional theory has been used productively so far in QM/MM approaches for the study of such systems, this methodology has limitations. Here we pursue for the first time a QM/MM description of the reaction center in the principal enzyme of oxygenic photosynthesis, Photosystem II, using multireference wave function theory for the high-level QM region. We identify best practices and establish guidelines regarding the rational choice of active space and appropriate state-averaging for the efficient and reliable use of complete active space self-consistent field (CASSCF) and the N-electron valence state perturbation theory (NEVPT2) in the prediction of low-lying excited states of chlorophyll and pheophytin pigments. Given that the Gouterman orbitals are inadequate as a minimal active space, we define specific minimal and extended active spaces for the NEVPT2 description of electronic states that fall within the Q and B bands. Subsequently, we apply our multireference-QM/MM protocol to the description of all pigments in the reaction center of Photosystem II. The calculations reproduce the electrochromic shifts induced by the protein matrix and the ordering of site energies consistent with the identity of the primary donor (ChlD1) and the experimentally known asymmetric and directional electron transfer. The optimized protocol sets the stage for future multireference treatments of multiple pigments, and hence for multireference studies of charge separation, while it is transferable to the study of any photoactive embedded tetrapyrrole system.
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Affiliation(s)
- Maria Drosou
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Sinjini Bhattacharjee
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Bedogni M, Giavazzi D, Di Maiolo F, Painelli A. Shining Light on Inverted Singlet-Triplet Emitters. J Chem Theory Comput 2024; 20:902-913. [PMID: 37992126 PMCID: PMC10809715 DOI: 10.1021/acs.jctc.3c01112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023]
Abstract
The inversion of the lowest singlet and triplet excited states, observed in several triangle-shaped organic molecules containing conjugated carbon and nitrogen atoms, is an astonishing result that implies the breakdown of Hund's rule. The phenomenon attracted interest for its potential toward triplet harvesting in organic LEDs. On a more fundamental vein, the singlet-triplet (ST) inversion sheds new light on the role of electron correlations in the excited-state landscape of π-conjugated molecules. Relying on the celebrated Pariser-Parr-Pople model, the simplest model for correlated electrons in π-conjugated systems, we demonstrate that the ST inversion does not require triangle-shaped molecules nor any specific molecular symmetry. Indeed, the ST inversion does not require strictly non-overlapping HOMO and LUMO orbitals but rather a small gap and a small exchange integral between the frontier orbitals.
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Affiliation(s)
- Matteo Bedogni
- Department of Chemistry, Life Science
and Environmental Sustainability, Università
di Parma, 43124 Parma, Italy
| | - Davide Giavazzi
- Department of Chemistry, Life Science
and Environmental Sustainability, Università
di Parma, 43124 Parma, Italy
| | - Francesco Di Maiolo
- Department of Chemistry, Life Science
and Environmental Sustainability, Università
di Parma, 43124 Parma, Italy
| | - Anna Painelli
- Department of Chemistry, Life Science
and Environmental Sustainability, Università
di Parma, 43124 Parma, Italy
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Karmakar N, Das M. Low-lying excited states of Diphenylpolyenes and its derivatives in singlet fission : A Density Matrix Renormalization Group study. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Naskar S, Das M. Effects of low-lying excitations in pentalene and its derivatives in singlet fission: a model exact and density matrix renormalisation group study. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1895346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sumit Naskar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
| | - Mousumi Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
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Energy ordering of singlet and triplet excited states in indacenodithiophene and indenofluorenes molecules in singlet fission: A model exact and density matrix renormalization group study. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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7
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Naskar S, Das M. The use of low-lying excited states of zethrene and its homologs in singlet fission within Pariser-Parr-Pople model Hamiltonian: A Density Matrix Renormalization Group study. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
We introduce a computational approach to study porphyrin-like transition metal complexes, bridging density functional theory and exact many-body techniques, such as the density matrix renormalization group (DMRG). We first derive a multi-orbital Anderson impurity Hamiltonian starting from first principles considerations that qualitatively reproduce generalized gradient approximation (GGA)+U results when ignoring inter-orbital Coulomb repulsion U ′ and Hund exchange J. An exact canonical transformation is used to reduce the dimensionality of the problem and make it amenable to DMRG calculations, including all many-body terms (both intra- and inter-orbital), which are treated in a numerically exact way. We apply this technique to FeN 4 centers in graphene and show that the inclusion of these terms has dramatic effects: as the iron orbitals become single occupied due to the Coulomb repulsion, the inter-orbital interaction further reduces the occupation, yielding a non-monotonic behavior of the magnetic moment as a function of the interactions, with maximum polarization only in a small window at intermediate values of the parameters. Furthermore, U ′ changes the relative position of the peaks in the density of states, particularly on the iron d z 2 orbital, which is expected to affect the binding of ligands greatly.
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Das M. Low-Lying Excited States in Thiophene-Based Cyclic Molecule Suitable for Optoelectronics: A Density Matrix Renormalization Group Study. ACS OMEGA 2018; 3:12253-12259. [PMID: 31459300 PMCID: PMC6644912 DOI: 10.1021/acsomega.8b01470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/14/2018] [Indexed: 06/10/2023]
Abstract
The low-lying excited states of thiophene-based cyclic oligomer tetrathia[22]annulene[2,1,2,1] (TTA) are studied using the density matrix renormalization group technique within long-range Pariser-Parr-Pople (PPP) model Hamiltonian. The calculated lowest singlet dipole-allowed excited state S1 (optical gap) is at 1.76 eV for TTA which is in very good agreement with experiment (1.6 eV), and therefore it is found to be promising in harvesting the visible to near-infrared region of the solar spectrum. The calculated diradical character of TTA and the lowest triplet to lowest singlet (T1/S1) ratio (0.12) in TTA obtained within the model PPP Hamiltonian suggest TTA to be a promising singlet fission material. Donor-acceptor (D-A) substitution in TTA also modulates the optical gap from 1.76 to 1.35 eV rendering (D-A)-substituted TTA applicable in organic light-emitting devices.
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Affiliation(s)
- Mousumi Das
- Department of Chemical Sciences and Centre for Advanced Functional Materials, (CAFM), Indian Institute of Science Education and Research
Kolkata, Mohanpur 741246, India
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Ben Amor N, Soupart A, Heitz MC. Methodological CASPT2 study of the valence excited states of an iron-porphyrin complex. J Mol Model 2017; 23:53. [DOI: 10.1007/s00894-017-3226-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 01/12/2017] [Indexed: 10/20/2022]
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Fransson T, Saue T, Norman P. Four-Component Damped Density Functional Response Theory Study of UV/Vis Absorption Spectra and Phosphorescence Parameters of Group 12 Metal-Substituted Porphyrins. J Chem Theory Comput 2016; 12:2324-34. [DOI: 10.1021/acs.jctc.6b00030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas Fransson
- Department
of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Trond Saue
- Laboratoire
de Chimie et Physique Quantiques, UMR 5626, CNRS — Université Toulouse III-Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse, France
| | - Patrick Norman
- Department
of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden
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Kerridge A. A RASSCF study of free base, magnesium and zinc porphyrins: accuracy versus efficiency. Phys Chem Chem Phys 2013; 15:2197-209. [PMID: 23296122 DOI: 10.1039/c2cp43982d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The restricted-active-space self-consistent-field methodology is successfully applied to the study of free base- and regular metalloporphyrins, the latter containing magnesium and zinc central ions. It is shown that inclusion of all excitations involving the Gouterman frontier orbitals in the RAS2 subspace results in a numerically stable approach, producing highly accurate results at a fraction of the computational cost of the complete-active-space self-consistent-field method, whereas increasing RAS2 beyond this size leads to only modest improvement. Topological and orbital analysis shows that the approach is also able to give a highly accurate description of the electronic wavefunction. Inclusion of the entire π-conjugated subsystem in the active space results in more accurate excitation energies and a reduction in the dependence on the exact form of the perturbational Hamiltonian used to include dynamic correlation. The larger active space also resolves a quantitative disagreement in results obtained with and without the inclusion of dynamic correlation.
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Affiliation(s)
- Andrew Kerridge
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
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Wouters S, Limacher PA, Van Neck D, Ayers PW. Longitudinal static optical properties of hydrogen chains: Finite field extrapolations of matrix product state calculations. J Chem Phys 2012; 136:134110. [DOI: 10.1063/1.3700087] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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