Large-scale correlated study of excited state absorptions in naphthalene and anthracene

Sony, Priya; Shukla, Alok

doi:10.1063/1.3159670

Cited by 21 publications

(17 citation statements)

References 37 publications

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“…1 denote the electron-electron repulsion terms, with the parameters U , and V ij representing the on-site, and the long-range Coulomb interactions, respectively. The matrix elements t ij depicts one-electron hops, which in our calculations, have been restricted to nearest neighbours, with the value t 0 = 2.4 eV, consistent with our earlier calculations on conjugated polymers, [23][24][25][26][27][28][29] and polyaromatic hydrocarbons. 30,31 Parameterization of the Coulomb interactions is done according to the Ohno relationship 54…”

Section: Computational Detailssupporting

confidence: 88%

Theory of linear optical absorption in diamond-shaped graphene quantum dots

2015

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In this paper, optical and electronic properties of diamond shaped graphene quantum dots (DQDs) have been studied by employing large-scale electron-correlated calculations. The computations have been performed using the π-electron Pariser-Parr-Pople model Hamiltonian, which incorporates long-range Coulomb interactions. The influence of electroncorrelation effects on the ground and excited states has been included by means of the configuration-interaction approach, used at various levels. Our calculations have revealed that the absorption spectra are red-shifted with the increasing sizes of quantum dots. It has been observed that the first peak of the linear optical absorption, which represents the optical gap, is not the most intense peak. This result is in excellent agreement with the experimental data, but in stark contrast to the predictions of the tight-binding model, according to which the first peak is the most intense peak, pointing to the importance of electron-correlation effects. 1 arXiv:1501.06041v3 [cond-mat.mes-hall]

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Section: Computational Detailssupporting

confidence: 88%

Theory of linear optical absorption in diamond-shaped graphene quantum dots

2015

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“…For both the ground and the excited states, these calculations were performed in an iterative manner, until the optical absorption spectra computed from them converged. We have extensively used this approach in our earlier calculations on conjugated polymers [24-27] as well as on B 12 icosahedral and quasi-planar clusters reported recently [28]. …”

Section: Theoretical Methodologymentioning

confidence: 99%

Probing Aromaticity of Borozene Through Optical and Dielectric Response: A Theoretical Study

Sahu

Shukla

2010

Nanoscale Res Lett

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In this work, we report electronic structure calculations aimed at computing the linear optical absorption spectrum and static dipole polarizablity of a newly proposed boron-based planar aromatic compound borozene (B12H6). For the purpose, we use the semiempirical INDO model Hamiltonian, accompanied by large-scale correlation calculations using the multi-reference singles-doubles configuration-interaction (MRSDCI) approach. We present detailed predictions about the energetics, polarization properties, and the nature of many-particle states contributing to various peaks in the linear absorption spectrum. Our results can be used to characterize this material in future optical absorption experiments. We also argue that one can deduce the aromaticity of the cluster from the optical absorption and static polarizability results.

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“…21,23,24,26,29 Some theoretical calculations have predicted a symmetric ground state geometry to be lower, 21,29 while others have indicated a highly non-uniform geometry to be the true ground state. 23,24,26 In this work, consistent with the PPP model based work of Ramasesha and coworkers, 21,29 and our own work, 27,28 we have used the symmetric ground state geometry for all oligoacenes, with all the C-C bonds equal to 1.4 Å, and all bond angles taken to be 120 o . In order to investigate the influence of geometry on the optical absorption spectra, we performed calculations on nonacene using a highly non-uniform geometry reported for its closed-shell singlet ground state by Bendikov et al, 23 obtained using the B3LYP exchange-correlation functional in DFT.…”

Section: Influence Of the Geometry On The Optical Absorption In Long mentioning

confidence: 98%

Pariser–Parr–Pople Model Based Investigation of Ground and Low-Lying Excited States of Long Acenes

Chakraborty

Shukla

2013

J. Phys. Chem. A

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Several years ago, Angliker et al. [ Chem. Phys. Lett. 1982 , 87 , 208 ] predicted nonacene to be the first linear acene with the triplet state 1(3)B2u as the ground state, instead of the singlet 1(1)Ag state. However, contrary to that prediction, in a recent experimental work, Tönshoff and Bettinger [ Angew. Chem. Int. Ed. 2010 , 49 , 4125 ] demonstrated that nonacene has a singlet ground state. Motivated by this experimental finding, we decided to perform a systematic theoretical investigation of the nature of the ground and the low-lying excited states of long acenes, with an emphasis on the singlet-triplet gap, starting from naphthalene, all the way up to decacene. The methodology adopted in our work is based upon the Pariser-Parr-Pople model (PPP) Hamiltonian, along with the large-scale multireference singles-doubles configuration interaction (MRSDCI) approach. Our results predict that even though the singlet-triplet gap decreases with the increasing conjugation length, nevertheless, it remains finite till decacene, thus providing no evidence of the predicted singlet-triplet crossover. We also analyze the nature of many-particle wave function of the correlated singlet ground state and find that the longer acenes exhibit a tendency toward an open-shell singlet ground state. Moreover, when we compare the experimental absorption spectra of octacene and nonacene with their calculated singlet and triplet absorption spectra, we observe excellent agreement for the singlet case. Hence, the optical absorption results also confirm the singlet nature of the ground state for longer acenes. Calculated triplet absorption spectra of acenes predict two well-separated intense long-axis polarized absorptions, against one such peak observed for the singlet case. This is an important prediction regarding the triplet optics of acenes, which can be tested in future experiments on oriented samples.

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Large-scale correlated study of excited state absorptions in naphthalene and anthracene

Cited by 21 publications

References 37 publications

Theory of linear optical absorption in diamond-shaped graphene quantum dots

Theory of linear optical absorption in diamond-shaped graphene quantum dots

Probing Aromaticity of Borozene Through Optical and Dielectric Response: A Theoretical Study

Pariser–Parr–Pople Model Based Investigation of Ground and Low-Lying Excited States of Long Acenes

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