Size-scaling behaviour of the electronic polarizability of one-dimensional interacting systems

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Title: Size-scaling behaviour of the electronic polarizability of one-dimensional interacting systems
Authors: Chiappe, Guillermo | Louis, Enrique | Vergés Brotons, José Antonio
Research Group/s: Física de la Materia Condensada | Materiales Avanzados
Center, Department or Service: Universidad de Alicante. Departamento de Física Aplicada | Universidad de Alicante. Instituto Universitario de Materiales
Keywords: Polarizability | Metal-insulator transition | Charge gap | Hubbard model | Long-range hopping model | Poly-acetylene
Knowledge Area: Física Aplicada | Física de la Materia Condensada
Issue Date: 6-Apr-2018
Publisher: IOP Publishing
Citation: Journal of Physics: Condensed Matter. 2018, 30: 175603. doi:10.1088/1361-648X/aab85d
Abstract: Electronic polarizability of finite chains is accurately calculated from the total energy variation of the system produced by small but finite static electric fields applied along the chain direction. Normalized polarizability, that is, polarizability divided by chain length, diverges as the second power of length for metallic systems but approaches a constant value for insulating systems. This behaviour provides a very convenient way to characterize the wave-function malleability of finite systems as it avoids the need of attaching infinite contacts to the chain ends. Hubbard model calculations at half filling show that the method works for a small U  =  1 interaction value that corresponds to a really small spectral gap of 0.005 (hopping t  =  −1 is assumed). Once successfully checked, the method has been applied to the long-range hopping model of Gebhard and Ruckenstein showing 1/r hopping decay (Gebhard and Ruckenstein 1992 Phys. Rev. Lett. 68 244; Gebhard et al 1994 Phys. Rev. B 49 10926). Metallicity for U values below the reported metal-insulator transition is obtained but the surprise comes for U values larger than the critical one (when a gap appears in the spectral density of states) because a steady increase of the normalized polarizability with size is obtained. This critical size-scaling behaviour can be understood as corresponding to a molecule which polarizability is unbounded. We have checked that a real transfer of charge from one chain end to the opposite occurs as a response to very small electric fields in spite of the existence of a large gap of the order of U for one-particle excitations. Finally, ab initio quantum chemistry calculations of realistic poly-acetylene chains prove that the occurrence of such critical behaviour in real systems is unlikely.
Sponsor: Financial support by the Spanish Ministerio de Economía y Competitividad (MINECO) (grants FIS2015-64222-C2-1-P and FIS2015-64222-C2-2-P) is gratefully acknowledged.
ISSN: 0953-8984 (Print) | 1361-648X (Online)
DOI: 10.1088/1361-648X/aab85d
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2018 IOP Publishing Ltd
Peer Review: si
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Appears in Collections:INV - LMA - Artículos de Revistas
INV - Física de la Materia Condensada - Artículos de Revistas

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