(changelog)=

# Changelog

## Version 1.0.0

* Enable calculations with local electron-phonon coupling on the impurity site.
  Parameters of the local phonon can be passed to `EDIpackSolver.__init__()`
  via the keyword argument `phonon` of a special type `PhononParams`.
  Computed expectation values of phonon-related observables are available via
  new properties of `EDIpackSolver`: `phonon_occ` for the phonon mode occupancy,
  `phonon_x` for the expectation value of the phonon displacement operator, and
  `phonon_x2` for the expectation value of its square. Matsubara and
  real-frequency Green's functions of the phonon are available via properties
  `EDIpackSolver.phonon_D_iw` and `EDIpackSolver.phonon_D_w`.

* Expose single-particle density matrix of the full system (impurity + bath)
  via read-only property `EDIpackSolver.denmat`.

* Expose impurity reduced density matrix via read-only property
  `EDIpackSolver.rdm`. Calculation of the reduced density matrix is enabled
  by passing `rdm=True` to `EDIpackSolver.solve()`.

* Added a read-only property `EDIpackSolver.bath_op` that returns the current
  bath stored in the solver in the form of a TRIQS operator.
  The returned object contains contributions from both the bath Hamiltonian and
  the impurity-bath hybridization Hamiltonian.

## Version 0.11.0

* A matrix basis for the bath Hamiltonian in the general bath topology mode can
  now be explicitly specified. The basis is passed via the `bath_basis` keyword
  argument of `EDIpackSolver`'s constructor as a list of TRIQS many-body
  operator objects. Each operator is expected to be quadratic in bath electron
  creation/annihilation operators (both normal and anomalous terms are allowed).
  The list must include all basis operators for all replicas in no specific
  order, although - due to a limitation of EDIpack - subsets of operators for
  all replicas must be equivalent.

* Enable selection of symmetry sectors of the Hamiltonian considered for
  diagonalization. This feature is activated by a new boolean flag `ed_sectors`
  passed as a keyword argument to `EDIpackSolver.__init__()`. Selected sectors
  can be specified via a new read/write attribute `EDIpackSolver.sectors`.
  The attribute is a list of pairs `(N_{up}, N_{dn})` for `EDMode.NORMAL`,
  of non-negative integers `N_{tot}` for `EDMode.NONSU2`, or of integers `S_z`
  for `EDMode.SUPERC`. By default, it is set to `None` and all sectors of the
  Hamiltonian are considered for diagonalization. Apart from that, 
  `EDIpackSolver.__init__()` now accepts another integer parameter
  `ed_sectors_shift` if `ed_sectors=True`.
  
* In order to reduce the number of keyword arguments of
  `EDIpackSolver.__init__()`, those of them related to the Lanczos algorithm
  (name prefix `lanc_`) have been grouped into a dataclass `LanczosParams`.

## Version 0.10.0

* Added an enumeration type `EDMode` that represents EDIpack's exact
  diagonalization mode.
* It is now possible to force a specific EDIpack diagonalization mode, as long
  as the requested mode is compatible with the one deduced from the Hamiltonian.
  The corresponding keyword argument of `EDIpackSolver`'s constructor is called
  `ed_mode`.
* Enable support for s-wave pairing terms in the impurity Hamiltonian.
* Semantics of `EDIpackSolver.hloc` has been changed. This attribute now gives
  access to the local impurity Hamiltonian in the form of a TRIQS many-body
  operator object. The object contains terms corresponding to both normal and
  anomalous pairing contributions.
* Alternatively, matrices of the normal local Hamiltonian and of the impurity
  pairing fields are now read-write accessible via new attributes
  `EDIpackSolver.hloc_mat` and `EDIpackSolver.hloc_an_mat`.

## Version 0.9.0

* Expose non-interacting impurity Green's functions and hybridization functions
  via attributes of `EDIpackSolver`.
* Expose dynamical susceptibilities (response functions) via attributes of
  `EDIpackSolver`. The attributes are called `chi_spin_{iw,w,tau}` for the spin
  channel, `chi_dens_{iw,w,tau}` for the charge channel, `chi_pair_{iw,w,tau}`
  for the pair channel, and `chi_exct_{iw,w,tau}` for the exciton channel.

## Version 0.8.0

* Add support for calculations without bath.
* Allow for read-write access to `EDIpackSolver.hloc`.
* `EDIpackSolver.superconductive_phi` has been changed to be the modulus of the
  computed superconductive order parameter. The complex argument of the order
  parameter is now accessible as `EDIpackSolver.superconductive_phi_arg`.
* `EDIpackSolver`'s constructor got a new keyword argument `keep_dir`, which
  disables automatic deletion of EDIpacks's temporary directory upon object
  destruction. This option is ignored on Python < 3.12.
* Do not ignore the argument `lanc_nstates_sector` of `EDIpackSolver`'s
  constructor in the zero temperature mode.
* Fixed a bug in `EDIpackSolver.chi2_fit_bath()`, which made this method
  unusable without first calling `EDIpackSolver.solve()`. There is now a unit
  test that covers the bath fitting functionality.

## Version 0.7.0

* Add support for general two-particle interactions.
* Add support for zero temperature calculations.

## Version 0.6.0

Updated codebase following the naming change of EDIpack2 and EDIpy2.
C.f. https://github.com/EDIpack/EDIpack/issues/16.

## Version 0.5.0

This is the initial public release for this project.