Spectroscopy & Electronic Structure

X-ray diffraction patterns, radial distribution functions, band structures, density of states, and Brillouin zone visualization.

Source: src/lib/xrd/, src/lib/rdf/, src/lib/bands/, src/lib/brillouin/

X-Ray Diffraction (XRD)

Compute powder XRD patterns from crystal structures.

Key Functions

// Calculate XRD pattern for a structure
calculate_xrd_pattern(structure, radiation?): XrdPattern

// Compare XRD patterns across multiple structures
calculate_xrd_structure(structures, radiation?): XrdComparison

Radiation Sources

Source	Wavelength (A)
Cu Ka	1.5406
Mo Ka	0.7107
Ag Ka	0.5609
W La	1.4764

Component

XrdPlot.svelte — Interactive XRD pattern display with peak labels, 2-theta range selection, and multi-structure overlay.

---

Radial Distribution Function (RDF)

Calculate pair correlation functions g(r) for structural analysis.

Key Functions

// RDF for a specific element pair
calculate_rdf(structure, options): RdfResult

// All pair RDFs at once
calculate_all_pair_rdfs(structure, options): Map<string, RdfResult>

Options

interface RdfOptions {
  cutoff: number          // Maximum distance (A)
  bins: number            // Number of histogram bins
  center_species?: string // Central element filter
  neighbor_species?: string // Neighbor element filter
  use_pbc: boolean        // Apply periodic boundary conditions
}

Component

RdfPlot.svelte — Line plot of g(r) vs distance with pair selection and smoothing.

---

Band Structure

Visualize electronic band structure E(k) along high-symmetry paths.

Components

Component	Description
Bands.svelte	Band structure E(k) line plot
Dos.svelte	Density of states plot
BandsAndDos.svelte	Combined side-by-side bands + DOS
BrillouinBandsDos.svelte	Brillouin zone + bands + DOS together

Data Format

interface BandData {
  kpoints: number[][]      // k-point coordinates
  eigenvalues: number[][]  // Energy values per band per k-point
  efermi: number           // Fermi energy (eV)
  labels: string[]         // High-symmetry point labels (Gamma, X, M, etc.)
  label_positions: number[] // x-coordinates of labels
}

interface DosData {
  energies: number[]       // Energy grid (eV)
  densities: number[]      // DOS values
  efermi: number           // Fermi energy (eV)
}

---

Brillouin Zone

Interactive 3D visualization of the first Brillouin zone with high-symmetry points and k-paths.

Key Functions

// Compute reciprocal lattice vectors
compute_reciprocal_lattice(lattice_matrix): number[][]

// Compute Brillouin zone polyhedron
compute_brillouin_zone(reciprocal_lattice): BrillouinZone

// Identify high-symmetry k-points
compute_high_symmetry_points(lattice_type): HighSymmetryPoints

// Get k-path coordinates for band structure
get_path_coords(bz, path_labels): PathCoords

Components

Component	Description
BrillouinZone.svelte	Main 3D viewer
BrillouinZoneScene.svelte	Three.js scene with zone faces, edges, and k-points
BrillouinZoneControls.svelte	Toggle faces, edges, labels, paths
BrillouinZoneInfoPane.svelte	Reciprocal lattice parameters
BrillouinZoneExportPane.svelte	Export visualization

Features

• Transparent polyhedron rendering
• High-symmetry point labels (Gamma, X, M, R, K, L, etc.)
• k-path visualization along the zone
• Interactive rotation and zoom
• Combined view with band structure and DOS