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Titolo:
Linking the atomistic scale and the mesoscale: molecular orbital and solidstate packing calculations on poly(p-phenylene)
Autore:
Rabias, I; Langlois, C; Provata, A; Howlin, BJ; Theodorou, DN;
Indirizzi:
Univ Surrey, Sch Phys & Chem, Dept Chem, Guildford GU2 5XH, Surrey, England Univ Surrey Guildford Surrey England GU2 5XH ord GU2 5XH, Surrey, England NRCPS Demokritos, Inst Phys Chem, Athens 15310, Greece NRCPS Demokritos Athens Greece 15310 nst Phys Chem, Athens 15310, Greece Univ Patras, Dept Chem Engn, Patras 26500, Greece Univ Patras Patras Greece 26500 as, Dept Chem Engn, Patras 26500, Greece
Titolo Testata:
POLYMER
fascicolo: 1, volume: 43, anno: 2002,
pagine: 185 - 193
SICI:
0032-3861(200201)43:1<185:LTASAT>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
STRUCTURAL PHASE-TRANSITION; CRYSTAL-STRUCTURE; ELECTRONIC-PROPERTIES; ENERGY CALCULATIONS; POLYPHENYLS; POLYPARAPHENYLENE; QUATERPHENYL; OLIGOMERS; POLYMERS; PLANAR;
Keywords:
molecular orbital; ab initio; molecular mechanics;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Howlin, BJ Univ Surrey, Sch Phys & Chem, Dept Chem, Guildford GU2 5XH, Surrey, England Univ Surrey Guildford Surrey England GU2 5XH , Surrey, England
Citazione:
I. Rabias et al., "Linking the atomistic scale and the mesoscale: molecular orbital and solidstate packing calculations on poly(p-phenylene)", POLYMER, 43(1), 2002, pp. 185-193

Abstract

The energies and structures of neutral benzenoid and neutral quinonoid polyphenylenes in the gas phase were calculated at the ab initio and semi-empirical levels for oligomers containing up to 11 rings as a function of the torsion angles between consecutive aromatic rings. In the gas-phase poly(p-phenylene) (PPP) simulations, a transition to the aromatic benzenoid structure occurs in the centre of chains as short as about six to seven rings. Thedevelopment of electronic properties such as ionisation potential, the carbon-carbon bond length between rings, the band gap and width of the highestoccupied bands were studied. On going from a coplanar to a perpendicular conformation, qualitatively, the ionisation potential and band gap values increase and the band widths of the highest occupied bands decrease. Molecular mechanics simulations were used to model the crystal structures of PPP oligomers using Lennard-Jones and sinusoidal torsion potentials, with parameters derived initially from the gas-phase calculations. These solid state simulations reproduced known crystal structures and predictions are made for the crystal structures of PPP oligomers up to a degree of polymerisation of11. The crystal packing forces the PPP molecules to be planar, hence increasing conductivity in the solid state. Interestingly, there is an anomaly in the packing energy results for the sexiphenylene case which is in accord with the gas phase calculations. (C) 2001 Elsevier Science Ltd. All rights reserved.

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Documento generato il 10/04/20 alle ore 02:38:37