Quantum Phonon Fluctuations in Mesoscopic Dimerized Systems

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XX7e describe quantitatively tlae strtmcttrr;'tl chatnge in firaite Peierls claarins. Ftrll qtranturn taaechanical calcvtlat,ions shoxv: (i) luoxv the suaaootlt phase transition occtrrs toy tlte contintrotrs change ofthe groutad state wave function which preserves tlue sytnttuetry of' tlue Haraailtonian; (ii) tlae strtrc-tttral claange is accornpanied Icy an anharxaaonicity xwlaich beconaaes very pronotrnced in the broadtrarrtsition region; (iii) tlae diunerization is strpjcressed for sizes sl?orter than 21 certaiza critical size.Quauattrrn phonotu flttctttations CQII uaaake the latter svxfficiex'xtly large ('vO.l - 1 p.na) to be detectedin mesoscopic systems (e.g, jcerylene radical cation salts) xvith wealcer electron-plaotaon coupling.As possible techniques for experinaetatal observsttiotu, xve suggest tl'xe nonlinear optical absorptionand the ttltrasonic ;tttentration. Otrr calctrla,Lions are based on uatrnaerical diagonalizattion doneexactly in srnall chains ?trtd xvithin tlae ardiatbatic ansatz for longer chains. XVe ir'xdicate l'lOW totest selJ'consiste'n.tly the latter restrlts atud sltoxv that they are accturate Lip to uaaesoscopic sizesiza parataaeter ranges of relevance f'or real s.3'stetns. XX'e explaira why cotax'entiotaal unany-taodytechtaiqtres are inappropriate to descrilce tlae Peierls transition in finite cl'uaiuus.
社団法人日本物理学会の論文
1999-06-15