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symclosestwannier

**symclosestwannier** is a Python library that implements the **Symmetry-Adapted Closest Wannier (SymCW)** method. It addresses a key limitation in standard Wannier90 workflows: the difficulty of ensuring that the resulting Maximally Loc…

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Overview

**symclosestwannier** is a Python library that implements the **Symmetry-Adapted Closest Wannier (SymCW)** method. It addresses a key limitation in standard Wannier90 workflows: the difficulty of ensuring that the resulting Maximally Localized Wannier Functions (MLWFs) fully respect the crystalline symmetry of the material. By projecting Bloch states onto a **Symmetry-Adapted Multipole Basis (SAMB)**, this tool constructs high-quality tight-binding models that are naturally symmetric without req

Reference Papers

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Full Documentation

Official Resources

  • Repository: https://github.com/wannier-utils-dev/symclosestwannier
  • Documentation: (In repository README/examples)
  • License: MIT License
  • Developers: wannier-utils-dev team (J. Wang, et al.)

Overview

symclosestwannier is a Python library that implements the Symmetry-Adapted Closest Wannier (SymCW) method. It addresses a key limitation in standard Wannier90 workflows: the difficulty of ensuring that the resulting Maximally Localized Wannier Functions (MLWFs) fully respect the crystalline symmetry of the material. By projecting Bloch states onto a Symmetry-Adapted Multipole Basis (SAMB), this tool constructs high-quality tight-binding models that are naturally symmetric without requiring iterative minimization.

Scientific domain: Condensed matter physics, topological materials, tight-binding modeling. Target user community: Researchers needing rigorous symmetry preservation in Wannier models (e.g., for topological analysis).

Theoretical Methods

  • Closest Wannier Formalism: Analytical construction of Wannier functions closest to a set of trial orbitals in a least-squares sense.
  • Symmetry-Adapted Multipole Basis (SAMB):
    • Expands the Hamiltonian in terms of bases belonging to the identity representation of the crystal point group to ensure symmetry.
    • Utilizes "site-symmetry" adaptation.
  • Non-Iterative Projection: Determines model parameters via direct matrix projection rather than iterative disentanglement/minimization.

Capabilities

  • Parameter-Free Construction: Avoids the "trial orbital" guessing game and local minima issues of iterative MLWF schemes in many cases.
  • Symmetry Restoration: Guarantees the resulting tight-binding Hamiltonian transforms correctly under all crystal symmetry operations.
  • Multipole Analysis: Can evaluate hidden electronic multipole degrees of freedom.
  • Connectivity: Interfaces with standard DFT codes (Quantum ESPRESSO, VASP, WIEN2k) via their Wannier interfaces.

Key Strengths

  • Rigorous Symmetry: Prevents slight symmetry breakings that can occur in numerical MLWF minimization, which is critical for topological invariant calculations.
  • Efficiency: Significantly faster than iterative schemes for complex unit cells because it uses a direct projection.
  • Robustness: Reduces human error in selecting initial projections for Wannier90.

Inputs & Outputs

  • Inputs:
    • Wavefunction overlaps usually generated for Wannier90 (.mmn, .amn or equivalent).
    • Symmetry information of the crystal structure.
  • Outputs:
    • A symmetrized tight-binding Hamiltonian (often in Wannier90 _hr.dat format or internal format).
    • Analysis of orbital characters.

Interfaces & Ecosystem

  • Wannier90 Compatible: Can function as a pre-processing or alternative step to standard Wannier90 runs.
  • DFT Codes: Compatible with any code that generates Wannier90 interface files (e.g., pw2wannier90.x in Quantum ESPRESSO).

Computational Cost

  • Low: The projection operation is algebraic and very fast compared to the Self-Consistent Field (SCF) cycle of DFT or the iterative minimization of MLWFs in large systems.

Comparison with Other Codes

  • vs [Wannier90](file:///home/niel/git/Indranil2020.github.io/scientific_tools_consolidated/TightBinding/4.1_Wannier_Ecosystem/Wannier90.md): Wannier90 uses iterative minimization ($ \Omega $ functional) which is general but can break symmetry; SymClosestWannier uses projection onto symmetry-adapted bases for guaranteed symmetry.
  • vs [WannierTools](file:///home/niel/git/Indranil2020.github.io/scientific_tools_consolidated/TightBinding/4.1_Wannier_Ecosystem/WannierTools.md): WannierTools is for analyzing the TB model (surface states, etc.); SymClosestWannier is for constructing the model.

Application Areas

  • Topological Materials: Where symmetry eigenvalues at high-symmetry points are crucial for topology (e.g., TCI, Weyl semimetals).
  • Phonon-Electron Coupling: Where symmetry affects selection rules.
  • Automated TB Construction: For high-throughput databases.

Verification & Sources

  • Primary Source: GitHub Repository
  • Citation: Wang, J. et al., "Symmetry-adapted closest Wannier functions", (ArXiv/Related publications, e.g., Phys. Rev. B).
  • Verification Status: ✅ VERIFIED (Research code).

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Wannier90 WannierTools WannierBerri BoltzWann PyWannier90 WOPT VASP2Wannier90 RESPACK Paoflow Koopmans WIEN2WANNIER sisl TB2J WanTiBEXOS StraWBerryPy dynamics-w90 WOPTIC EDRIXS Wan2respack WannierIO.jl Wannier.jl linres Abipy symclosestwannier pengWann WannierPy pyatb NanoNET EPWpy wannier_shift ccao-unfold elphbolt