Formation and hopping motion of molecular polarons

被引:15
作者
Emin, D [1 ]
机构
[1] Univ New Mexico, Dept Phys & Astron, Albuquerque, NM 87131 USA
来源
PHYSICAL REVIEW B | 2000年 / 61卷 / 21期
关键词
D O I
10.1103/PhysRevB.61.14543
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
This paper addresses polaron formation and intermolecular hopping of a carrier confined to molecules immersed within a polar medium. Three types of polaron state are possible: (i) The carrier can encompass ail equivalent sires of the occupied molecule. (ii) The carrier can be localized at a single atomistic unit of the molecule. (iii) If the carrier's interactions with the medium's ions are strong enough, the self-trapped carrier can be localized among a subset of the molecule's equivalent sites. High-temperature intermolecular hopping requires the formation of a coincidence configuration in which the carrier is shared between the jump's two molecules, The hop's activation energy depends on the expansion of a molecule's carrier as it approaches a coincidence from its minimum-energy configuration. The carrier's intramolecular motion in response to atoms' motions also reduces these atoms' vibrational frequencies thereby lowering their vibrational free energy. This carrier-induced vibrational softening affects the temperature-independent coefficient of the Arrhenius jump rate. Thus carrier's intrasite motion, ignored in Holstein's model, can significantly affect small-polaron formation and hopping.
引用
收藏
页码:14543 / 14553
页数:11
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