mps-0.0.0
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itebd_aklt_state.cc
1 // -*- mode: c++; fill-column: 80; c-basic-offset: 2; indent-tabs-mode: nil -*-
2 /*
3  Copyright (c) 2012 Juan Jose Garcia Ripoll
4 
5  Tensor is free software; you can redistribute it and/or modify it
6  under the terms of the GNU Library General Public License as published
7  by the Free Software Foundation; either version 2 of the License, or
8  (at your option) any later version.
9 
10  This program is distributed in the hope that it will be useful,
11  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  GNU Library General Public License for more details.
14 
15  You should have received a copy of the GNU General Public License along
16  with this program; if not, write to the Free Software Foundation, Inc.,
17  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19 
20 #include <mps/itebd.h>
21 
22 namespace mps {
23 
25  {
26  // From "The density-matrix renormalization group in
27  // the age of matrix product states",
28  // Ulrich Schollwoeck, Annals of Physics 326, 96 (2011)
29  RTensor A = RTensor::zeros(igen << 2 << 3 << 2);
30  // A(,0,) = sqrt(2/3) \sigma^+
31  A.at(0,0,1) = sqrt(2.0/3.0);
32  // A(,1,) = Pauli_z
33  A.at(0,1,0) = -sqrt(1.0/3.0);
34  A.at(1,1,1) = sqrt(1.0/3.0);
35  // A(,2,) = sqrt(2/3) \sigma^-
36  A.at(1,2,0) = -sqrt(2.0/3.0);
37  RTensor lA = RTensor::ones(igen << 2);
38  return RiTEBD(A, lA, A, lA);
39  }
40 
41 }
const RiTEBD infinite_aklt_state()
Infinitely long, one-dimensional AKLT state.
An infinite Matrix Product State with translational invariance but using two tensors: one for odd and...
Definition: itebd.h:41