Quantum rotor model: Difference between revisions

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The '''quantum rotor model''' is a mathematical model for a quantum system. It can be visualized as an array of rotating electrons which behave as [[rigid rotor]]s that interact through short-range dipole-dipole magnetic forces originating from their [[magnetic dipole moment]]s (neglecting [[Coulomb force]]s). The model differs from similar spin-models such as the [[Ising model]] and the [[Heisenberg model (quantum)|Heisenberg model]] in that it includes a term analogous to [[kinetic energy]]. See [[Langton'27s_ant#Wave_equation|wave equation model]].

Although elementary quantum rotors do not exist in nature, the model can describe effective [[Degrees of freedom (mechanics)|degrees of freedom]] for a system of sufficiently small number<!-- Is it possible to give an idea of "small number" ?--> of closely coupled [[electrons]] in low-energy states.<ref name="sachdev">{{Cite book|title=Quantum Phase Transitions |last=Sachdev |first=Subir |url=http://books.google.com/books?id=Ih_E05N5TZQC&printsec=frontcover |year=1999 |publisher=[[Cambridge University Press]] |isbn=978-0-521-00454-1 |page= |accessdate=2010-07-10}}</ref>