User.md

🔹 Input Variables

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🔸 CONTROL

category - options listed below
method - options listed below
outdir - where data is saved
indir - where data is read
prefix - beginning of all relevant input/output files
verbosity - low, high(default)

🔸 SYSTEM

interaction - vertex function. Options: (FLEX, EPC)
Temperature - units of eV
cell_type - Simple Cubic, Body Centered Cubic, Face Centered Cubic, Orthorhombic, Tetragonal, Hexagonal
onsite_U - Hubbard Repulsion value
nbnd - Number of bands
dimension - Dimension of system

🔸 MESH

k_mesh - Number of points in kx, ky, kz. Used as input for calculations on meshes (ie $E(k)$)
q_mesh - Number of points in qx, qy, qz. Used for mesh output (ie $\chi(q)$)
w_pts - Number of points in frequency. Used for Matsubara frequencies as well

🔸 CELL

3x3 lattice vectors (implicitly defined if given BRILLOUIN_ZONE)

🔸 BRILLOUIN_ZONE

3x3 reciprocal lattice vectors (implicitly defined if given CELL)

🔸 BANDS

FORMAT:

nbnd bands are listed in the format of:
    band1 = 'band_name'
        var = value
    band2 = 'band_name'
        var = value
    ...

VARIABLES:

band_names - 'fermi_gas', 'tight_binding'
    fermi_gas vars
        eff_mass
        shift
    tight_binding vars
        t0
        t1
        ...
        t10

🔹 Current Calculation Categories

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🔸 test (default)

• Purpose: Runs basic tests to confirm that all categories are functioning correctly.

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🔸 superconductor

• Purpose: Calculates superconducting gap size and symmetry.
• Options:
  • method:
    • bcs – Basic BCS approximation
      • Outputs _gap.dat file with gap values along surface
    • eliashberg – Eliashberg theory
      • Outputs _gap.dat file with gap values across brillouin zone
  • calculation:
    • diagonalization – Direct diagonalization of gap functions
    • projection – Projection onto a predefined basis set
  • FS_only:
    • true – Only compute gap on the Fermi surface
    • false – Compute over the entire Brillouin zone

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🔸 response

! Purpose: Computes bare susceptibility. ! Options: ! method:
! sparse_ir – Uses sparse Matsubara frequencies (finite T; requires dense k-grid)
- Outputs _chi.dat file with chi values across brillouin zone ! libtetrabz – Uses analytic tetrahedra integration (0 K; allows sparse grid)
- Outputs _chi.dat file with chi values across brillouin zone ! ⚠️ If you encounter "STOP NESTING", adjust the k-grid size. ! dynamic:
! true – Calculate and save data for finite $\omega$
! false – Only compute at $\omega = 0$ ! wpts:
! Number of Matsubara frequencies.
! wpts = 1 calculates only at $i\omega = 0$.

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🔸 vertex

• Purpose: Calculates a specific two-particle vertex function.
• Options:
  • interaction:
    • FLEX – Computes the FLEX vertex; requires bare susceptibility file (_chi.dat)
• Outputs _vertex.dat file with vertex values across brillouin zone

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🔸 DOS

• Purpose: Computes the Density of States.
• Options:
  • method:
    • libtetrabz – Analytic tetrahedra integration
    • surface_sum – Alternative method with comparable results
  • w_pts:
    • Number of energy points across bandwidth
  • k_mesh
    • Density of points when defining tetrahedra/surface points
• Outputs _DOS.dat file with Density of States vs Energy