Register package

[waltergu]

@JuliaRegistrator register()

Release notes:

QuantumClusterTheories v0.1.0

Initial release — the first public version of QuantumClusterTheories, a Julia package for quantum cluster theories in condensed matter physics.

Overview

QuantumClusterTheories implements a suite of quantum cluster methods, including Cluster Perturbation Theory (CPT) and Variational Cluster Approach (VCA), for computing single-particle Green's functions of strongly correlated quantum lattice models.

Key Features

• CPT frontend — High-level interface combining unit cell, lattice, impurity solver, perturbation, and periodization
• Periodization — Crystallographic periodization for restoring the broken lattice translation symmetry due to artificial cluster partitioning
• Abstract ImpuritySolver interface — Pluggable design allowing custom impurity solver implementations; subtyping requires only a solver(ω) method
• EDSolver (via extension) — Exact diagonalization solver using the BandLanczos method, with caching support for repeated queries
• Multi-system support — Fermionic, hard-core-bosonic, and spin systems
• Symbolic operator representation — Built on QuantumLattices for symbolic operator algebra; interfaces with TightBindingApproximation and ExactDiagonalization

Dependencies

• QuantumLattices (v0.14.5)
• TightBindingApproximation (v0.3.7)
• ExactDiagonalization (v0.3.1, weak dependency)

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/151570

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.1.0 -m "<description of version>" f4f447d6a97128968413febc6144c66c5f0981fe
git push origin v0.1.0

[waltergu]

@JuliaRegistrator register()

Release notes:

QuantumClusterTheories v0.1.0

Initial release — the first public version of QuantumClusterTheories, a Julia package for quantum cluster theories in condensed matter physics.

Overview

QuantumClusterTheories implements a suite of quantum cluster methods, including Cluster Perturbation Theory (CPT) and Variational Cluster Approach (VCA), for computing single-particle Green's functions of strongly correlated quantum lattice models.

Key Features

• CPT frontend — High-level interface combining unit cell, lattice, impurity solver, perturbation, and periodization
• Periodization — Crystallographic periodization for restoring the broken lattice translation symmetry due to artificial cluster partitioning
• Abstract ImpuritySolver interface — Pluggable design allowing custom impurity solver implementations; subtyping requires only a solver(ω) method
• EDSolver (via extension) — Exact diagonalization solver using the BandLanczos method, with caching support for repeated queries
• Multi-system support — Fermionic, hard-core-bosonic, and spin systems
• Symbolic operator representation — Built on QuantumLattices for symbolic operator algebra; interfaces with TightBindingApproximation and ExactDiagonalization

Dependencies

• QuantumLattices (v0.14.5)
• TightBindingApproximation (v0.3.7)
• ExactDiagonalization (v0.3.1, weak dependency)

[JuliaRegistrator]

Registration pull request updated: JuliaRegistries/General/151570

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.1.0 -m "<description of version>" d1c813e079c15190ea34d83bdb8bf9e1116bfe72
git push origin v0.1.0

[waltergu]

@JuliaRegistrator register()

Release notes:

Features

• ComposedEDSolver: New solver for handling composed systems that require stitching (ComposedEDSolver)
• DynamicalSpectra: New DynamicalSpectra type with Algorithm integration (d3743f7)
• ImpuritySolver and CPT update capability: Added update functionality for both ImpuritySolver and CPT (d3743f7)
• ImpuritySolver and CPT timing: Added qcttimer and the timer keyword argument for enhanced timing functionality (d67b985)

Documentation

• Added Haldane-Hubbard topological phase transition example documentation (cafef81)

Bug Fixes

• Fixed subhilbert and CPT operator issues in ImpuritySolver (e47d4bc)

Maintenance

• Refactored tests: separated test module and updated dependencies (ed5ca41)
• Updated QuantumLattices dependency to 0.14.6

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/151938

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.1.1 -m "<description of version>" 2d0f9b52c8ab04977fd8ee73616fd9249ca93caa
git push origin v0.1.1

[waltergu]

@JuliaRegistrator register()

Release notes:

New Features

• VCA (Variational Cluster Approach)

  • New VCAPerturbation type for Weiss field terms
  • New VCA alias for QCT with VCAPerturbation
  • New optimize! function for VCA grand potential optimization
  • New expectation function supporting symbol-based Weiss term selection

• Grand Potential (Ω) Computation

  • New Ω function for computing grand potential per unit cell
  • New factor helper for BdG normalization (factor=2 for BdG, 1 for TBA)
  • Solver-level Ω methods in EDSolver and ComposedEDSolver

• Enhanced Solver Functionality

  • inv method for ImpuritySolver, EDSolver, and ComposedEDSolver
  • Inverse Green's function caching for performance
  • Ground state energy tracking in EDSolver

Refactoring

• Major Module Restructure

  • Split QuantumClusterTheories.jl into Core.jl and Optimizer.jl
  • New Perturbation abstract type with CPTPerturbation and VCAPerturbation subtypes
  • QCT now generic frontend type, CPT and VCA are type aliases

• EDSolver/ComposedEDSolver Refactoring

  • Delayed initialization with cached G and G⁻¹ structures for Green's function and its inverse

• API Changes

  • matrix(perturbation, k) → perturbation(k) (call syntax)
  • update!(cpt; timer=...) now part of single update! call

Performance

• Optimized run! for DynamicalSpectra by precomputing perturbation matrices
• Inverse Green's function caching reduces redundant computations

Documentation

• Renamed HaldaneHubbardTopologicalPhaseTransition.md to HaldaneHubbard.md
• Created SquareHubbard.md with examples for:
  • Single-particle spectral function
  • Antiferromagnetic order (VCA)
  • d-wave superconductivity (VCA)
• Tightened optimization tolerances in examples

Dependencies

• ExactDiagonalization: 0.3.3 → 0.3.4
• QuantumLattices: 0.14.6 → 0.14.7
• TightBindingApproximation: 0.3.7

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/153567

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.1.2 -m "<description of version>" 02ae510430b6dced10f84e35f8fd840eb6a0e7e4
git push origin v0.1.2

[waltergu]

@JuliaRegistrator register()

Release notes:

New Features

ED solver caching via qlcsave/qlload

EDSolver now supports disk caching of expensive eigensystem results. On set!, the solver checks for a cached state matching the current configuration fingerprint (SHA-512 of content-to-config) and loads it if available, skipping the Lanczos diagonalization. When the cache is stale or absent, the eigensystem is computed and saved via qlcsave. This eliminates redundant diagonalization when re-running the same cluster calculation.

ImpuritySolver subtypes Frontend

ImpuritySolver is now a subtype of Frontend, integrating it into the QuantumLattices frontend hierarchy. It also defines Base.valtype(::Type{<:ImpuritySolver}) = Matrix{ComplexF64}, enabling generic code to query the value type.

Refactoring

Adaptation to QuantumLattices 0.15.0 type hierarchy

• Removed unused plain/lazy/eager imports from Generator calls across CPTPerturbation, VCAPerturbation, and the ED extension — these keyword arguments are no longer part of the upstream Generator API.
• expand(weiss.system, m) in VCA expectation is now wrapped with an explicit Generator(...) call to construct a proper TBA system for matrix extraction.

Dependency Updates

• QuantumLattices: bumped from 0.14.7 to 0.15.0
• TightBindingApproximation: bumped from 0.3.7 to 0.3.8
• ExactDiagonalization: bumped from 0.3.4 to 0.3.5
• Julia compat remains 1.10 - 1.12

Other Changes

• Expanded .gitignore to cover generated artifacts (.png, .dat, .dlm, .qld, .qlc) and IDE directories (.vscode, .claude)
• Added valtype test for ImpuritySolver in the Core test suite

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/155746

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.1.3 -m "<description of version>" c0ee164ee1be745a5b78d9fc8563774bc4546807
git push origin v0.1.3

[waltergu]

@JuliaRegistrator register()

Release notes:

New Features

Operator-based CPT and VCA Constructors

New CPT and VCA constructors accept pre-computed unitcell OperatorSet (rank-2 operators, e.g. from Wannier90) together with separate rank-4 interaction terms (e.g. Hubbard). This enables workflows where non-interacting single-particle operators are computed externally and then augmented with correlation effects.

• CPT(unitcell, ops_unitcell::OperatorSet, lattice, hilbert, interactions, quantumnumbers; ...) — Constructs a CPT frontend from pre-computed unitcell operators and interaction terms.
• VCA(unitcell, ops_unitcell::OperatorSet, lattice, hilbert, interactions, weiss, quantumnumbers; ...) — Constructs a VCA frontend from pre-computed unitcell operators, interaction terms, and Weiss field terms.

A new testset "Operator-based CPT/VCA" validates these constructors against the existing "Square-Hubbard-VCA" benchmark.

ImpuritySolver with Pre-built OperatorGenerator

Two new ImpuritySolver constructors allow bypassing the internal ED building step:

• ImpuritySolver(ed::ED, operators, method; ...) — Constructs from a pre-built ED and operator list.
• ImpuritySolver(lattice, system::OperatorGenerator, quantumnumbers, method; ...) — Constructs from a pre-built OperatorGenerator.

embed() Helper Function

A new embed(unitcell, ops_unitcell::OperatorSet, lattice) function replicates unitcell operators onto the lattice. It returns a 4-tuple of (intraoperators, interoperators, intrabonds, interbonds), which enables clean separation of intracluster and intercluster contributions in operator-based CPT/VCA workflows.

Pre-built TBA Support in Perturbation

New Perturbation constructors accept pre-built TBA objects directly:

• Perturbation(intercluster::TBA) -> CPTPerturbation
• Perturbation(intercluster::TBA, weiss::TBA) -> VCAPerturbation

The VCAPerturbation type now includes an inner constructor with a TBAKind consistency assertion to catch mismatched subsystems at construction time.

Behavioral Changes

Cache Stamp Precision Increased

The signature stamp precision used in qlcsave/qlload has been increased from 10 to 14 decimal places. The previous 10-decimal-place rounding could produce identical cache keys for parameter changes smaller than ~5×10⁻¹¹, risking false cache hits during optimization finite differences and line-search backtracking. The new threshold of ~5×10⁻¹⁵ provides a ~3,000,000× safety margin over Optim.jl's forward-difference step size (~1.5×10⁻⁸), while remaining well above eps(Float64).

Rank Validation

• VCA interactions: Rank-4 assertion (all(==(4), map(rank, OneOrMore(interactions)))) ensures only proper interaction terms are passed to operator-based constructors.
• VCA weiss: Rank-2 assertion (all(==(2), map(rank, OneOrMore(weiss)))) ensures Weiss field terms are quadratic.
• VCAPerturbation: Kind consistency assertion between intercluster and weiss TBA subsystems.

Internal Refactoring

Module Reorganization

Imports (using/import statements) previously in src/QuantumClusterTheories.jl have been moved into src/Core.jl for local scope and reduced module-level coupling. The module file now serves purely as a top-level entry point.

Simplified Perturbation Construction

Perturbation constructors now delegate to the TBA constructor directly, removing the explicit Quadraticization/commutator boilerplate that was previously inlined. This follows the upstream refactoring in TightBindingApproximation.

Periodization Uses Solver Operators Directly

CPT and VCA constructors now reuse solver.operators for periodization instead of recomputing from kind(pert), reducing redundant operator construction.

Deprecated Imports Removed

Removed unused imports: EDKind, EDMatrixization, Sector, Table, Metric, Quadraticization, commutator.

Dependency Updates

Package	Old	New
ExactDiagonalization	0.3.5	0.3.6
QuantumLattices	0.15.0	0.15.3
TightBindingApproximation	0.3.8	0.3.9

Test Adjustments

• Added "Operator-based CPT/VCA" testset.
• Relaxed precision of several reference values (rounded from 15–16 to 7–8 significant digits) to match the adjusted atol tolerance and reduce sensitivity to numerical noise across dependency versions.
• AFM Néel VCA test: m-value changed from 0.3 to 0.2 for consistency with the operator-based CPT/VCA testset.