triqs.gfs.tools.delta

triqs.gfs.tools.delta(g)[source]

Hybridization function \(\Delta(i\omega_n)\) extracted from a non-interacting Green’s function.

Computes \(\Delta = i\omega_n - G_0^{-1}\) and removes the fitted constant tail so that \(\Delta(i\omega_n) \to 0\) at large frequencies.

Parameters:
gGf or BlockGf

Non-interacting Green’s function \(G_0\) on a Matsubara mesh, either matrix-valued or scalar-valued.

Returns:
Gf or BlockGf

Hybridization function on the same mesh as \(G_0\).

Notes

Assumes:

  • the diagonal components of \(G_0\) decay as \(1/i\omega_n\);

  • \(G_0\) is Hermitian, i.e. \(G_0(i\omega_n)_{ij} = \overline{G_0(-i\omega_n)_{ji}}\).

Prints a warning if the tail fit residual exceeds 1e-5.

Examples

>>> from triqs.gfs import delta
>>> Delta_iw = delta(G0_iw)