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Calculation of eigenvectors for quasi-one-dimensional disordered systems

โœ Scribed by B. Gazdy; R.S. Day; M. Seel; F. Martino; J. Ladik


Publisher
Elsevier Science
Year
1982
Tongue
English
Weight
284 KB
Volume
88
Category
Article
ISSN
0009-2614

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โœฆ Synopsis


A rcccntly proposed Green maIn\ method for the study of loL&zatlon phcnomcna m dlsordcrcd polymers IS gcncmllzcd As an ~JIustra~vc c\amplc the clcctromc cigcnslatc corresponding to two succcsstvc long bonds in an alternattng (Cl& than (conformatlonal sohlon) is calculated lnvestrgation of the properties of large dtsordered systems plays an increasmgly important role both m solid state and polymer phystcs. The large number of unit cells together with the lack of symmetry makes numerical calculations extremely drflicult. Usually, the first and most important task IS to calculate the densrty of states, to locate the energy levels corresponding to the impurtttcs, and to get mformation about the behaviour of the wavefunction at these energy levels (localizatron studres) An excellent review of several numerrcal methods for cafculatmg the spectra can be found in the book by Hon [I]. The method of negative factor counting (NFC) [3_] is especially well suited for quasi-one-dimensional chains [3]. Some calculations in whrch the propertres of the wavefunctrons m daordered systems were studted arc summarized rn ref. 141. Recently a new technique was proposed [S] whrch allows one to deduce the qualitative nature of the ergenstates for polymers if the eigenstate is localized nearer to one end of the chain. In this letter we generahze thrs method for eigenstates locahzed at the rrth unit of the quasi-one-drmensional system. The new technique can bc used both for investrgatmg the qualitative nature of an eigenstate and for calculating the eigenvector exphcitlyespecially if inverse Iteration [6] is not feasible due to the large dimension of the matrrx. As a test example we calculate the eigcnstate correspondmg to two successive long bonds m an alternating (CH), chain (soliton formation [7,8]) and show that for this sample case the new method gives the analytic results for the component of the Green matrix elements GtA,/GNN should be a good measure of the localization of an eigenstate localized near to the Nth unrt of the cham: the smaller the ratio of the Green matnx elements the more pronounced the locahzation. We are going to generalize tlus ratio showmg that * Prcsenl address Conoco Compagny, Oklahoma, USA.


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