Matrix Product Toolkit | Tools / MpIBcWavepacket

Create an real-space wavepacket from a solution to the MPS excitation ansatz [1].

Synopsis

mp-ibc-wavepacket [options] -w <input-prefix> -k <momentum-range> -o <psi-out>
mp-ibc-wavepacket [options] -w <input-prefix> --sma <momentum> -o <psi-out>

Options

--help

Show help message.

-w, --wavefunction

Prefix for the filenames of the input wavefunctions, of the form [prefix].k[k] (required).

-k, --momentum

Momentum range of input wavefunctions, of the form start:end:stop or start:end,num, in units of {$\pi$} (required).

--sma

Use a single-mode approximation for the excitation using the input wavefunction of this momentum (alternative to specifying the full momentum range with -k).

--ky

Use this {$y$}-momentum range to localise the wavepacket on a cylinder (filenames must then be of the form [prefix].kx[k].ky[ky]).

--digits

Force the input filenames to use this many decimal places in the momentum.

--latticeucsize

Use this value for the lattice unit cell size for determining momenta (defaults to the wavefunction attribute LatticeUnitCellSize, or 1 otherwise).

-o, --output

Filename for the output wavefunction.

-f, --force

Force overwriting the output file if it already exists.

-s, --sigma

Convolute the real-space wavepacket with a Gaussian in momentum space with this width, in units of {$\pi$}.

-c, --kcenter

The central momentum for the momentum space Gaussian, in units of {$\pi$} (default 0).

--sigmay

If using --ky, convolute the real-space wavepacket with a Gaussian in {$y$}-momentum space with this width, in units of {$\pi$}.

--kycenter

The central momentum for the {$y$}-momentum space Gaussian, in units of {$\pi$} (default 0).

--tol

Tolerance for the wavepacket amplitude outside of the window: this is used to determine the minimum size window to represent the wavepacket (default 1e-5).

--min-states

Minimum bond dimension of the window after truncation (default 0).

--max-states

Maximum bond dimension of the window after truncation (default 100000).

-r, --trunc

The truncation error cutoff threshold when truncating the state (alternative to -d).

-d, --eigen-cutoff

The singular value cutoff threshold when truncating the state.

-v, --verbose

Increase verbosity.

Description

This tool creates a real-space wavepacket from a set of solutions of the MPS excitation ansatz over a range of momenta using the algorithm presented in Ref. [1].

References

[1] M. Van Damme, L. Vanderstraeten, J. De Nardis, J. Haegeman, F. Verstraete, Real-time scattering of interacting quasiparticles in quantum spin chains, Phys. Rev. Research 3, 013078 (2021), doi:10.1103/PhysRevResearch.3.013078, arXiv:1907.02474.