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The mp-allcorrelation command quickly calculates a correlation function within a single unit cell of an iMPS.


mp-allcorrelation [options] <psi> <operator1> <operator2>

Calculates all expectation values {$\langle O_1(i) \vert \psi \vert O_2(j) \rangle$} for {$i < j$}, labelled by lattice unit cells. Operator1 and operator2 must have support over a single lattice unit cell.



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-c, --cart

Show the results in Cartesian coordinates

-p, --polar

show the results in polar coordinates

-r, --real

Show the real part of the result

-i, --imag

show the imaginary part of the result

-m, --mag

Show the magnitude part of the result

-a, --arg

show the argument part of the result


show the argument in radians

-l, --lattice

As an alternative to specifying the lattice separately for each operator, you can set it once here and it will implicitly use this lattice, as if you used the syntax lattice:operator


don't show the preamble or column headings

-v, --verbose

Enable debug output (can be used more than once)


Calculates all expectation values {$\langle O_1(i) \vert \psi \vert O_2(j) \rangle$} for {$i < j$}.

Here, i and j are unit cell indices. The wavefunction must have a unit cell that is larger than the lattice unit cell. The operators must have support over a single unit cell.

Currently this tool only works for infinite systems -- it could be extended to work for finite or IBC as well.

Currently this tool ignores fermion signs. Don't use this tool with fermionic operators.


  1. In this example, we start from a spin-1/2 lattice (1-site unit cell), and construct a 10-site wavefunction.

    spinchain-u1 -o lat
    mp-idmrg-s3e -H lat:H_J1 -u 10 -w psi -m 10..50x100 --create -f -q 0

    Now we calculate all correlations within the 10-site wavefunction unit cell,
    mp-allcorrelation -l lat psi "Sz(0)" "Sz(0)"
  2. Should include another example with a larger lattice unit cell


  1. WARNING: do not use with fermion models. The implementation doesn't use the JW strings because these will become implicit with the new quantum number library (at which point fermions will magically start working).

See also

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Page last modified on July 04, 2020, at 07:02 PM