{ "id": "1008.2037", "version": "v1", "published": "2010-08-12T03:50:09.000Z", "updated": "2010-08-12T03:50:09.000Z", "title": "Coherent potential approximation of random nearly isostatic kagome lattice", "authors": [ "Xiaoming Mao", "T. C. Lubensky" ], "comment": "15 pages, 8 figures", "journal": "Physical Review E 83, 011111 (2011)", "doi": "10.1103/PhysRevE.83.011111", "categories": [ "cond-mat.dis-nn", "cond-mat.soft", "cond-mat.stat-mech" ], "abstract": "The kagome lattice has coordination number $4$, and it is mechanically isostatic when nearest neighbor ($NN$) sites are connected by central force springs. A lattice of $N$ sites has $O(\\sqrt{N})$ zero-frequency floppy modes that convert to finite-frequency anomalous modes when next-nearest-neighbor ($NNN$) springs are added. We use the coherent potential approximation (CPA) to study the mode structure and mechanical properties of the kagome lattice in which $NNN$ springs with spring constant $\\kappa$ are added with probability $\\Prob= \\Delta z/4$, where $\\Delta z= z-4$ and $z$ is the average coordination number. The effective medium static $NNN$ spring constant $\\kappa_m$ scales as $\\Prob^2$ for $\\Prob \\ll \\kappa$ and as $\\Prob$ for $\\Prob \\gg \\kappa$, yielding a frequency scale $\\omega^* \\sim \\Delta z$ and a length scale $l^*\\sim (\\Delta z)^{-1}$. To a very good approximation at at small nonzero frequency, $\\kappa_m(\\Prob,\\omega)/\\kappa_m(\\Prob,0)$ is a scaling function of $\\omega/\\omega^*$. The Ioffe-Regel limit beyond which plane-wave states becomes ill-define is reached at a frequency of order $\\omega^*$.", "revisions": [ { "version": "v1", "updated": "2010-08-12T03:50:09.000Z" } ], "analyses": { "subjects": [ "46.65.+g", "05.70.Jk", "61.43.-j", "62.20.de" ], "keywords": [ "coherent potential approximation", "isostatic kagome lattice", "average coordination number", "spring constant", "central force springs" ], "tags": [ "journal article" ], "publication": { "publisher": "APS", "journal": "Physical Review E", "year": 2011, "month": "Jan", "volume": 83, "number": 1, "pages": "011111" }, "note": { "typesetting": "TeX", "pages": 15, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011PhRvE..83a1111M" } } }