Documentation:Bose Glass

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The Bose glass model

The following parameter file sets up a Monte Carlo simulation of the quantum Bose Hubbard model with a random site dependent chemical potential on a square lattice using the worm code. The chemical potential is drawn from an uniform distribution in the range [-5,+5].

LATTICE="inhomogeneous square lattice";
L=4;

MODEL="boson Hubbard";
NONLOCAL=0;
U    = 1.0;
Nmax = 2;
t = 1.0;
T = 0.1;
delta = 5.0;
SWEEPS=500000;
THERMALIZATION=10000;

{ DISORDERSEED = 34275; mu=delta*2*(random()-0.5); }
{ DISORDERSEED = 49802; mu=delta*2*(random()-0.5); }
{ DISORDERSEED = 82529; mu=delta*2*(random()-0.5); }

In order to use periodic boundary conditions you have to adjust the boundary type of the inhomogeneous square lattice in the lattice.xml file:

<LATTICEGRAPH name = "inhomogeneous square lattice">
  <FINITELATTICE>
    <LATTICE ref="square lattice"/>
    <PARAMETER name="W" default="L"/>
    <EXTENT dimension="1" size="L"/>
    <EXTENT dimension="2" size="W"/>
    <BOUNDARY type="periodic"/>
  </FINITELATTICE>
  <UNITCELL ref="simple2d"/>
  <INHOMOGENEOUS><VERTEX/></INHOMOGENEOUS>
</LATTICEGRAPH>

You can run the simulation by using the same sequence of commands as in the worm algorithm tutorial.