Use of semiempirical models for calculation of <i>B</i> terms in MCD spectra. II. The Pariser-Parr-Pople (PPP) model: A consequence of the pairing symmetry in π systems with alternant skeletons

Michl, Josef

doi:10.1063/1.1681729

Cited by 23 publications

(6 citation statements)

References 21 publications

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“…In other words, it has an indisputable physical origin. The importance of the approximate selection rules which result from this symmetry has been long recognized in one-photon absorption and emission spectroscopy [26], magnetic circular dichroism [27], two-photon absorption spectroscopy [28], etc.…”

Section: B Alternance Symmetrymentioning

confidence: 99%

“…The bipartite nature of alternant systems gives rise to a particle-hole symmetry in the single * josep.planelles@uji.es; http://quimicaquantica.uji.es/ particle energy spectrum which is missing in nonalternant systems. As a result, molecules of the each kind share features of the electronic structure whose impact on the reactivity and spectroscopy have been long recognized [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

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Role of alternance symmetry in magnetoconductance

Planelles

Climente

2014

Phys. Rev. B

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We show that the direction of coherent electron transport across a cyclic system of quantum dots or a cyclic molecule can be modulated by an external magnetic field if the cycle has an odd number of hopping sites, but the transport becomes completely symmetric if the number is even. These contrasting behaviors, which remain in the case of interacting electrons, are a consequence of the absence or presence of alternance symmetry in the system. These findings are relevant for the design of nanocircuits based on coupled quantum dots or molecular junctions.

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Section: B Alternance Symmetrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of alternance symmetry in magnetoconductance

Planelles

Climente

2014

Phys. Rev. B

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“…If the commutator of the Hamiltonian H, and the magnetic dipole operator is proportional to the linear momentum operator, a similar relationship involving magnetic dipole transitions can be derived [ 121. Also, the so-called "B-term," which is the most significant term in the magnetic circular dichroism (MCD) of organic molecules, can be shown to change signs if anionic and cationic eigenstates are interchanged [25]. There is no need to treat explicitly these and similar properties, since they all follow from the above basic relations.…”

Section: Classical Properties Of Alternant Systemsmentioning

confidence: 99%

“…The set (24), or equivalently the set (25), contains all two-particle ASA operators. We have obtained explicit expressions for all two-particle alternant, and for all twoparticle antialternant, operators.…”

Section: ~Ivkovicmentioning

confidence: 99%

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Alternant systems and their properties

Živković

1987

Int J of Quantum Chemistry

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Neutral, ionic, and complete alternant systems are studied using the alternancy symmetry adapted (ASA) approach. This approach is based on an explicit construction of ASA operators that are up to the sign invariant with respect to the particle-hole symmetry transformation. These operators serve as building blocks of alternant systems, and they determine their characteristic properties. All Hamiltonians describing neutral alternant systems are explicitly constructed. Up to some minor restrictions, all Hamiltonians descGbing ionic and complete alternant systems are also explicitly constructed. Inversely, given a Hamiltonian H in a second quantization notation, one can easily check whether or not this Hamiltonian describes a neutral (ionic, complete) alternant system. All linear properties characteristic to neutral (ionic, complete) alternant systems are obtained. In particular, all one-and two-particle properties are derived in an explicit form. The properties obtained substantially generalize "classical" properties of alternant systems such as, in the case of neutral alternant systems, uniform charge density distribution, vanishing bond orders between atomic sites of the same parity, and alternancy selection rules for the electric dipole transitions.

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Magnetic Circular Dichroism of π Systems

Michl

1998

Encyclopedia of Computational Chemistry

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Use of semiempirical models for calculation of B terms in MCD spectra. II. The Pariser-Parr-Pople (PPP) model: A consequence of the pairing symmetry in π systems with alternant skeletons

Abstract: Within the PPP model, MCD spectra of two 7T-electron species which are paired in the sense of alternant symmetry are mirror images of each other. Consequences of this theorem for the understanding of MCD spectra of substituted alternant hydrocarbons are pointed out.

Cited by 23 publications

References 21 publications

Role of alternance symmetry in magnetoconductance

Role of alternance symmetry in magnetoconductance

Alternant systems and their properties

Magnetic Circular Dichroism of π Systems

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