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MpAllcorrelation

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

Synopsis

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.

Options

--help

-c, --cart

-p, --polar

-r, --real

-i, --imag

-m, --mag

-a, --arg

--radians

-l, --lattice

--quiet

-v, --verbose

Description

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.

Examples

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

Notes

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

• MpExpectation
• MpICorrelation