Electronic excitations of C60 fullerene calculated using the <i>ab initio</i> cluster expansion method

Fukuda, Ryoichi; Ehara, Masahiro

doi:10.1063/1.4757066

Cited by 15 publications

(11 citation statements)

References 42 publications

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“…The band gap of C 60 measured in films is 1.7 eV 144 (0.062 hartree) and in liquids 1.82 eV 138 (0.067 hartree), values that agree fairly well with the separation between the HOMO and the LVVO (or C 60 's very similar valence LCMO) for both pure DFAs, an indication that both the occupied and empty orbital have the same "DFA upshift". Clearly, research into more meaningful eigenvalues from DFA calculations is important but is not the central theme of this paper, which is concerned with the separation of the empty orbital space into valence and nonvalence orbitals.…”

supporting

confidence: 60%

“…The LCMO occurs at ε = −0.0232 hartree, has the correct t 1u symmetry, and is only slightly larger spatially than the LVVO which has a nearly identical pseudoeigenvalue. However, the rest of C 60 's unoccupied CMO level diagram consists of numerous diffuse orbitals and resembles a continuum starting at zero energy (see ref 138 for a typical C 60 CMO spectrum).…”

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confidence: 99%

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Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept

2015

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Many chemical concepts hinge on the notion of an orbital called the lowest unoccupied molecular orbital, or LUMO. This hypothetical orbital and the much more concrete highest occupied molecular orbital (HOMO) constitute the two "frontier orbitals", which rationalize a great deal of chemistry. A viable LUMO candidate should have a sensible energy value, a realistic shape with amplitude on those atoms where electron attachment or reduction or excitation processes occur, and often an antibonding correspondence to one of the highest occupied MOs. Unfortunately, today's quantum chemistry calculations do not yield useful empty orbitals. Instead, the empty canonical orbitals form a large sea of orbitals, where the interesting valence antibonds are scrambled with the basis set's polarization and diffuse augmentations. The LUMO is thus lost within a continuum associated with a detached electron, as well as many Rydberg excited states. A suitable alternative to the canonical orbitals is proposed, namely, the valence virtual orbitals. VVOs are found by a simple algorithm based on singular value decomposition, which allows for the extraction of all valence-like orbitals from the large empty canonical orbital space. VVOs are found to be nearly independent of the working basis set. ABSTRACT: Many chemical concepts hinge on the notion of an orbital called the lowest unoccupied molecular orbital, or LUMO. This hypothetical orbital and the much more concrete highest occupied molecular orbital (HOMO) constitute the two "frontier orbitals", which rationalize a great deal of chemistry. A viable LUMO candidate should have a sensible energy value, a realistic shape with amplitude on those atoms where electron attachment or reduction or excitation processes occur, and often an antibonding correspondence to one of the highest occupied MOs. Unfortunately, today's quantum chemistry calculations do not yield useful empty orbitals. Instead, the empty canonical orbitals form a large sea of orbitals, where the interesting valence antibonds are scrambled with the basis set's polarization and diffuse augmentations. The LUMO is thus lost within a continuum associated with a detached electron, as well as many Rydberg excited states. A suitable alternative to the canonical orbitals is proposed, namely, the valence virtual orbitals. VVOs are found by a simple algorithm based on singular value decomposition, which allows for the extraction of all valence-like orbitals from the large empty canonical orbital space. VVOs are found to be nearly independent of the working basis set. The utility of VVOs is demonstrated for construction of qualitative MO diagrams, for prediction of valence excited states, and as starting orbitals for more sophisticated calculations. This suggests that VVOs are a suitable realization of the LUMO, LUMO + 1, ... concept. VVO generation requires no expert knowledge, as the number of VVOs sought is found by counting s-block atoms as having only a valence s orbital, transition metals as having valence s and d, and main ...

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confidence: 99%

Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept

2015

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“…Indeed, it is known that TDDFT sometimes underestimates the energy differences of low-lying excited states of conjugated systems with several degenerate states such as porphyrines and fullerenes. [25,27,28] In the following, we focus on the first three singlet excitations in pyridine, resulting from B3LYP/6-31 + + G** calculations. As the ground state is a singlet, only singlet excitations can have a non-zero oscillator strength.…”

Section: Ground State and Excited State Properties Of Pyridine And Nimentioning

confidence: 99%

Structural and Photophysical Properties of Various Polypyridyl Ligands: A Combined Experimental and Computational Study

et al. 2020

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Covalent triazine frameworks (CTFs) with polypyridyl ligands are very promising supports to anchor photocatalytic complexes. Herein, we investigate the photophysical properties of a series of ligands which vary by the extent of the aromatic system, the nitrogen content and their topologies to aid in selecting interesting building blocks for CTFs. Interestingly, some linkers have a rotational degree of freedom, allowing both a trans and cis structure, where only the latter allows anchoring. Therefore, the influence of the dihedral angle on the UV-Vis spectrum is studied. The photophysical properties are investigated by a combined computational and experimental study. Theoretically, both static and molecular dynamics simulations are performed to deduce ground-and excited state properties based on density functional theory (DFT) and time-dependent DFT. The position of the main absorption peak shifts towards higher wavelengths for an increased size of the π-system and a higher π-electron deficiency. We found that the position of the main absorption peak among the different ligands studied in this work can amount to 271 nm; which has a significant impact on the photophysical properties of the ligands. This broad range of shifts allows modulation of the electronic structure by varying the ligands and may help in a rational design of efficient photocatalysts.

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“…The α‐band has very low intensity, while the intensity of the β‐band is very high. The SAC‐CI calculations for large PAH such as C 60 fullerene and extended coronenes have been reported; however, systematic studies on oligoacenes by the SAC‐CI have not been reported before, although the EOM‐CC study is available …”

Section: Resultsmentioning

confidence: 99%

Efficiency of perturbation-selection and its orbital dependence in the SAC-CI calculations for valence excitations of medium-size molecules

Fukuda

Ehara

2014

J. Comput. Chem.

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The efficiency and accuracy of the perturbation-selection used in the symmetry-adapted cluster-configuration interaction (SAC-CI) calculations are investigated for several low-lying valence excited states of 21 medium-size molecules, including typical chromophores with heterocyclic macrocycles (free-base porphine, coumarin, indole, and BODIPY), nucleobases, amino acids (tyrosine and tryptophan), polycyclic aromatic hydrocarbons, and organometallics (ferrocene and Re(bpy)(CO)4+1). Benchmark SAC-CI calculations with up to 110 million operators are performed. The efficiency of the perturbation-selection depends on the molecular orbitals (MOs); therefore, the canonical MO and localized MO (LMO) obtained by Pipek-Mezey's method are examined. Except for the highly symmetric molecules, using LMOs improves the efficiency and accuracy of the perturbation-selection. With using LMOs and perturbation-selection, sufficiently reliable results can be obtained in less than 10% of the computational costs required for the full-dimensional calculations. The perturbation-selection with LMOs is suggested to be a promising method for excited states in larger molecular systems.

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Electronic excitations of C60 fullerene calculated using the ab initio cluster expansion method

Cited by 15 publications

References 42 publications

Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept

Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept

Structural and Photophysical Properties of Various Polypyridyl Ligands: A Combined Experimental and Computational Study

Efficiency of perturbation-selection and its orbital dependence in the SAC-CI calculations for valence excitations of medium-size molecules

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