Exact Solution of the PPP Model for Correlated Electronic States of Tetracene and Substituted Tetracene

Pati, Y. Anusooya; Ramasesha, S.

doi:10.1021/jp502813w

Cited by 11 publications

(13 citation statements)

References 42 publications

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“…40,42,45,50 Upon comparing with the experiments, the best estimates of the excitation energies of the dipole-allowed states, 1 3 B − 1g , and 1 3 A − g , are 3.30 eV, and 3.84 eV , respectively, obtained in our standard parameter calculation. 44 and their E(1 3 B + 2u ) value of 1.22 eV is in excellent agreement with our standard parameter result obtained using the QCI approach. Theoretical calculations by other authors predict this energy to be in the range 1.10-1.51 eV.…”

Section: Anthracenesupporting

confidence: 89%

“…As shown in Table III, theoretical values of this quantity computed by other authors also exhibit wide variation, with our standard parameter results being in perfect agreement with the PPP-FCI values reported by Pati and Ramasesha. 44 On comparing with the liquid phase experiments, the best theoretical estimates of the excitation energies for the states 1 3 B − 1g and 1 3 A − g , 2.79 eV and 3.91eV, respectively, are from our screened parameter calculations.…”

Section: Tetracenementioning

confidence: 88%

“…3.05 2.79 2.92(g), 23 2.69(l), 26 2.68(l), 21 2.55(l) 27 3.07, 44 2.97, 45 3.16, 40 2.51 50 26 3.66(l), 21 3.01(l) 27 3.82, 44 Our screened parameter value of 1.97 eV matches exactly with the solution phase results, 21 while the standard parameter value of 2.06 eV is in between the two experimental values.…”

Section: Naphthalenementioning

confidence: 99%

See 2 more Smart Citations

Theory of triplet optical absorption in oligoacenes: From naphthalene to heptacene

Chakraborty

Shukla

2014

The Journal of Chemical Physics

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In this paper we present a detailed theory of the triplet states of oligoacenes containing up to seven rings, i.e., starting from naphthalene all the way up to heptacene. In particular, we present results on the optical absorption from the first triplet excited state 1 3 B + 2u of these oligomers, computed using the Pariser-Parr-Pople (PPP) model Hamiltonian, and a correlated electron approach employing the configuration-interaction (CI) methodology at various levels. Excitation energies of various triplets states obtained by our calculations are in good agreement with the experimental results, where available. The computed triplet spectra of oligoacenes exhibits rich structure dominated by two absorption peaks of high intensities, which are well separated in energy, and are caused by photons polarized along the conjugation direction. This prediction of ours can be tested in future experiments performed on oriented samples of oligoacenes.

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Section: Anthracenesupporting

confidence: 89%

Section: Tetracenementioning

confidence: 88%

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Theory of triplet optical absorption in oligoacenes: From naphthalene to heptacene

Chakraborty

Shukla

2014

The Journal of Chemical Physics

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“…How likely are the higher acenes to be good candidates for singlet fission that can be used in photovoltaics? Three thermodynamic criteria are often used in an analysis (29,110). The first criterion is E(S 1 ) > 2E(T 1 ).…”

Section: St Energy Gapmentioning

confidence: 99%

Nature of ground and electronic excited states of higher acenes

Yang

Davidson

Yang

2016

Proc. Natl. Acad. Sci. U.S.A.

174

208

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Higher acenes have drawn much attention as promising organic semiconductors with versatile electronic properties. However, the nature of their ground state and electronic excited states is still not fully clear. Their unusual chemical reactivity and instability are the main obstacles for experimental studies, and the potentially prominent diradical character, which might require a multireference description in such large systems, hinders theoretical investigations. Here, we provide a detailed answer with the particleparticle random-phase approximation calculation. The 1 A g ground states of acenes up to decacene are on the closed-shell side of the diradical continuum, whereas the ground state of undecacene and dodecacene tilts more to the open-shell side with a growing polyradical character. The ground state of all acenes has covalent nature with respect to both short and long axes. The lowest triplet state 3 B 2u is always above the singlet ground state even though the energy gap could be vanishingly small in the polyacene limit. The bright singlet excited state 1 B 2u is a zwitterionic state to the short axis. The excited 1 A g state gradually switches from a doubleexcitation state to another zwitterionic state to the short axis, but always keeps its covalent nature to the long axis. An energy crossing between the 1 B 2u and excited 1 A g states happens between hexacene and heptacene. Further energetic consideration suggests that higher acenes are likely to undergo singlet fission with a low photovoltaic efficiency; however, the efficiency might be improved if a singlet fission into multiple triplets could be achieved.higher acenes | diradical | double excitation | particle-particle random-phase approximation | charge-transfer excitation

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“…where t is hopping strength between nearest neighbor sites, i is the on-site energy for different atomic sites, U is the Hubbard interaction term and V g represents the external gate bias. We consider only nearest neighbor hopping and have taken equal hopping strength (2.4 eV) for all bonds, i.e., B-C, C-N and B-N 10,21 . Here, we neglect the small differences among the hopping parameters which may appear due to different chemical nature of C, B and N atoms.…”

Section: Model and Methodsmentioning

confidence: 99%

Small Heterocyclic Molecule as Multistate Transistor: A Quantum Many-body Approach

Ghosh¹,

Parida²,

Pati³

2020

Preprint

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Weakly coupled molecular junctions are quite active and important field of research as they exhibit various non-linear transport phenomena. We have investigated the carrier transport through weakly coupled B 2 C 2 N 2 H 6 molecules using quantum many body approach coupled with kinetic (master) equations. Various types of non-linear current voltage characteristics, such as, negative differential conductance (NDC), rectifications, Coulomb staircase, which are hallmark of multistate transport devices, have been obtained. Source-drain voltage induces changes in the occupation probabilities of low-lying many body states depending on the nature of the carrier transport.The nature of the carrier transport directly controls the net current flowing through the molecular junctions. We further investigated the effect of different kinds of perturbations such as application of gate voltage and magnetic field perpendicular to the direction of the molecule upon the carrierflow through various molecular bridges. Interestingly, we find that depending on the strength of the applied perturbing field, several phenomena, such as, switching off of the current, suppression of NDC etc. appears in the device. Fundamentally, this applied perturbation modifies both the site charge density as well as occupation probabilities of transport active channels, resulting in significant alteration in the transport behavior of the molecular junction.

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Exact Solution of the PPP Model for Correlated Electronic States of Tetracene and Substituted Tetracene

Cited by 11 publications

References 42 publications

Theory of triplet optical absorption in oligoacenes: From naphthalene to heptacene

Theory of triplet optical absorption in oligoacenes: From naphthalene to heptacene

Nature of ground and electronic excited states of higher acenes

Small Heterocyclic Molecule as Multistate Transistor: A Quantum Many-body Approach

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