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Extend the window(s) of an EA wavefunction.


mp-ea-extend [options] <psi-in> <psi-out>

Brief description



Show help message.

-n, --num

Extend the window(s) by this many sites to the right (default 1).

-f, --force

Force overwriting the output file if it already exists.

-v, --verbose

Increase verbosity.


This tool creates a copy of the EA wavefunction psi-in, and creates a copy of it in psi-out with the windows expanded by incorporating {$N$} sites into the right end of the window from the right boundary. (If psi-in and psi-out are the same file, then this will simply just extend its own windows.)

This is useful for increasing the accuracy of the excitation by increasing the size of the window and then optimising with mp-ea-dmrg?. However, note that in most cases the main limiting factor on the accuracy of the excitation will be the accuracy of the background wavefunction. The situations where extending the window are the most useful are when the background wavefunction is already the exact ground state with a small bond dimension (e.g. the AKLT state), or when the excitation is significantly broadened, such as for a single-particle mode near a multi-particle continuum.


  • At the moment, we only support incorporating sites into the right-hand side of the windows, since we assume the windows are written in the left gauge-fixing condition. Adding sites to the left-hand side of the window could be easily implemented, if it is ever needed.
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Page last modified on October 17, 2023, at 07:26 AM