"Six-vertex model and Quantum XXZ Hamiltonian"의 두 판 사이의 차이

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42번째 줄: 42번째 줄:
 
<h5 style="line-height: 2em; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;">transfer matrix formalism and the role of Bethe ansatz</h5>
 
<h5 style="line-height: 2em; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;">transfer matrix formalism and the role of Bethe ansatz</h5>
  
*  one can regard the down arrows in a row as 'particles'<br>
+
*  one can regard the up(or down) arrows in a row as 'particles'<br>
*  because of the ice rule, their number is conserved and one can try a Bethe ansatz for the eigenvectors of the transfer matrix<br>
+
*  because of the ice rule, their number is conserved and one can try a [[Bethe ansatz]] for the eigenvectors of the transfer matrix<br>
 
*   <br>
 
*   <br>
  
57번째 줄: 57번째 줄:
 
*  Hamiltonian of XXZ model or XXZ spin chain with  anisotropic parameter <math>\Delta=1/2</math><br><math>\hat H = -\sum_{j=1}^{N} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \Delta \sigma_j^z \sigma_{j+1}^z)</math><br>
 
*  Hamiltonian of XXZ model or XXZ spin chain with  anisotropic parameter <math>\Delta=1/2</math><br><math>\hat H = -\sum_{j=1}^{N} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \Delta \sigma_j^z \sigma_{j+1}^z)</math><br>
 
* ground state eigevector for Hamiltonian  is a common eigenvector although the eigenvalues are different
 
* ground state eigevector for Hamiltonian  is a common eigenvector although the eigenvalues are different
* see [YY
+
* see '''[YY1966-2]'''
  
 
 
 
 
187번째 줄: 187번째 줄:
 
* [http://dx.doi.org/10.1103/PhysRevLett.18.692 Exact Solution of the Problem of the Entropy of Two-Dimensional Ice]<br>
 
* [http://dx.doi.org/10.1103/PhysRevLett.18.692 Exact Solution of the Problem of the Entropy of Two-Dimensional Ice]<br>
 
** E. H. Lieb, Phys. Rev. Letters 18, 692 (1967)
 
** E. H. Lieb, Phys. Rev. Letters 18, 692 (1967)
* [http://dx.doi.org/10.1103/PhysRev.150.327 One-Dimensional Chain of Anisotropic Spin-Spin Interactions. II. Properties of the Ground-State Energy Per Lattice Site for an Infinite System]<br>
+
* '''[YY1966-2]'''[http://dx.doi.org/10.1103/PhysRev.150.327 One-Dimensional Chain of Anisotropic Spin-Spin Interactions. II. Properties of the Ground-State Energy Per Lattice Site for an Infinite System]<br>
** C. N. Yang, C. P. Yang, 1966
+
** C. N. Yang, C. P. Yang, Phys. Rev. 150, 327 (1966)
  
 
* [http://dx.doi.org/10.1016/0031-9163(66)91024-9 One-dimensional chain of anisotropic spin-spin interactions]<br>
 
* [http://dx.doi.org/10.1016/0031-9163(66)91024-9 One-dimensional chain of anisotropic spin-spin interactions]<br>
** C. N. Yang, C. P. Yang, Phys. Rev. 150, 321 (1966)
+
** C. N. Yang, C. P. Yang, Phys. Rev. 150, 321 (1966)
 
* http://dx.doi.org/10.1103/PhysRev.150.327
 
* http://dx.doi.org/10.1103/PhysRev.150.327
  

2010년 8월 3일 (화) 13:01 판

introduction
  • ice-type model, R model, Rys model
  • XXZ spin chain and the six-vertex transfer matrix have the same eigenvectors
  • Boltzmann weights
  • monodromy matrix
  • trace of monodromy matrix is the transfer matrix
  • power of transfer matrix becomes the partition function

 

 

types of six vertex models
  • on a square lattice with periodic boundary conditions
  • on a square lattice with domain wall boundary conditions

 

 

transfer matrix
  • borrowed from transfer matrix in statistical mechanics
  • transfer matrix is builtup from matrices of  Boltzmann weights
  • finding eigenvalues and eigenvectors of transfer matrix is crucial
  • Bethe ansatz equation is used to find the eigenvectors and eigenvalues of the transfer matrix
  • partition function = trace of power of transfer matrices
  • so the partition function  is calculated in terms of the eigenvalues of the transfer matrix
  • then the problem of solving the model is reduced to the computation of this trace

 

 

 

transfer matrix formalism and the role of Bethe ansatz
  • one can regard the up(or down) arrows in a row as 'particles'
  • because of the ice rule, their number is conserved and one can try a Bethe ansatz for the eigenvectors of the transfer matrix
  •  

 

 

 

anistropic one-dimensional Heisenberg model (XXZ model)
  • Heisenberg spin chain model
  • Hamiltonian of XXZ model or XXZ spin chain with  anisotropic parameter \(\Delta=1/2\)
    \(\hat H = -\sum_{j=1}^{N} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \Delta \sigma_j^z \sigma_{j+1}^z)\)
  • ground state eigevector for Hamiltonian  is a common eigenvector although the eigenvalues are different
  • see [YY1966-2]

 

 

 

 

Sutherland's observation
  • the eigenvectors of the transfer matrix depended on a,b,c only via the parameter
    \(\Delta=\frac{a^2+b^2-c^2}{2ab}\)
  • is the \delta = anistropic parameter in Heisenberg spin chain model ?

 

 

 

entropy of two-dimensional ice
  • entropy is given as
    \(Mk\ln W\) where M is the number of molecules and \(W=(4/3)^{3/2}=1.53960\cdots\)

 

 

 

free energy
  • \(F=-kT \ln Z\)

 

 

partition function

 

 

correlation functions

 

 

related items

 

 

books

 

 

encyclopedia

 

 

blogs

 

 

STATISTICAL MECHANICS-A REVIEW OF

SELECTED RIGOROUS RESULTS1•2

By JOEL L. LEBOWITZ

 

 

Method for calculating finite size corrections in Bethe ansatz systems: Heisenberg chain and six-vertex model
de Vega, H. J.; Woynarovich, F.

 

 

articles

 


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