\(\chi^2\) Fit

The module E2I_BATH_FIT includes a function to extend the bath optimisation to the case of multiple user baths corresponding to each inequivalent impurity. Where possible the optimization is parallel with respect to the impurities. See the module ED_BATH_FIT for further information about the fit for a single impurity.

Description

Contains routines that fit the Impurity model bath

Quick access

Routines:

ed_chi2_fitgf()

Used modules

• edipack2: EDIpack2.0 library frontend

• e2i_vars_global: Global variables, inequivalent sites version

• e2i_aux_funx: Assortment of auxiliary procedures, inequivalent sites version

External modules

• sf_constants

• sf_optimize

  • fmin_cg()

  • fmin_cgplus()

  • fmin_cgminimize()

• sf_linalg

  • eye()

  • zeye()

  • inv()

  • inv_her()

  • operator(.x.)()

• sf_iotools

  • reg()

  • free_unit()

  • txtfy()

• sf_arrays

  • arange()

• sf_misc

  • assert_shape()

• mpi

• sf_mpi

Subroutines and functions

interface  e2i_bath_fit/ed_chi2_fitgf(g, bath, f[, ispin])

This subroutine realizes the \(\chi^2\) fit of the Weiss field or hybridization function via an impurity model non-interacting Green's function. The bath levels (levels/internal structure and hybridization strength) are supplied by the user in the bath array and are the parameters of the fit. The function(s) to fit can have different shapes:

• [nlat \(\cdot\) nspin \(\cdot\) norb, nlat \(\cdot\) nspin \(\cdot\) norb, lfit ]

• [nlat, nspin \(\cdot\) norb, nspin \(\cdot\) norb, lfit ]

• [nlat, nspin, nspin, norb, norb, lfit ]

where nlat is the number of impurity sites in real-space DMFT. Accordingly, the bath array or arrays have rank 2 or 3. Some global variables directly influence the way the fit is performed and can be modified in the input file. See ed_input_vars for the description of lfit, cg_method , cg_grad, cg_ftol, cg_stop , cg_niter , cg_weight , cg_scheme , cg_pow , cg_minimize_ver , cg_minimize_hh .

Parameters:

• g (various shapes) [complex]

• bath (•, •) [real, inout]

• f (various shapes) [complex]

Options:

ispin [integer]