QE-Kit

A Pre- & Post-Processing Suite for Quantum ESPRESSO Developed by: Farhan Noor, University of Dhaka

QE-Kit is a comprehensive, modular Python and Bash toolkit designed to automate the workflow of Density Functional Theory (DFT) calculations using Quantum ESPRESSO. It bridges the gap between raw crystallographic data and publication-ready physical properties, featuring an interactive CLI, smart pseudopotential management, and robust XML-based calculation state verification.

🚀 Features

• Interactive & Headless Modes: Navigate via a beautiful, interactive CLI using questionary, or run modules headlessly in HPC batch scripts (e.g., ./qekit.py --305).
• State-Aware Generation: Modules parse QE XML schemas to ensure prerequisite calculations were successful before generating downstream inputs.
• Smart Pseudopotential Linking: Automatically detects local .UPF files or fetches them from your global library based on strict element mapping.
• Advanced Workflows: Built-in support for standard DFT, Electron-Phonon Coupling (EPC) for superconductivity, and thermodynamic/elastic property extraction via thermo_pw.

📂 Architecture & Modules

The suite is divided into four primary "Zones" and a foundational "Utils" layer.

🟢 ZONE 1 | Structural Discovery (Pre-Processing)

Focuses on preparing the initial crystalline structure and matching it with correct pseudopotentials.

• 100: structure2in: Converts raw crystallographic data (like .cif files) into a foundational scf.dat template. Defines the ibrav, CELL_PARAMETERS, ATOMIC_SPECIES, and ATOMIC_POSITIONS blocks.
• 101: pseudo_select: A "smart" pseudopotential linker. Reads scf.dat and checks if required .UPF files exist locally. If found, it natively assigns pseudo_dir='./'. If missing, it prompts the user to select functional/relativistic options from the global QE-POTCAR library, rigorously maps filenames to elements, and injects the absolute path.
• 102: kpath_gen: Generates high-symmetry K-point paths for the Brillouin zone, necessary for band structure and phonon dispersion calculations.

🔵 ZONE 2 | Input File Architect

Focuses on reading the scf.dat template and generating specific, execution-ready .in files for Quantum ESPRESSO binaries.

• 200: scf_gen: Generates the ground-state Self-Consistent Field (scf.in) input file.
• 201: vcrelax_gen: Generates the variable-cell relaxation input (vc-relax.in) for structural optimization.
• 202: nscf_gen: Generates the Non-Self-Consistent Field input (nscf.in), setting up dense uniform grids required for DOS or Fermi surface runs.
• 203: pdos_gen: Generates the projwfc.in file to calculate the Projected Density of States.
• 204: bands_gen: Generates the bands.in file to calculate electronic band dispersion along the k-path.
• 205: optical_gen: Generates inputs for optical properties (e.g., for epsilon.x).
• 206: phonon_gen: Generates the input file for Density Functional Perturbation Theory (ph.x) calculations.
• 207: fs_gen: Generates fs.in for the fs.x executable. Utilizes check_calc_status to ensure the parent NSCF calculation completed successfully before writing the file.
• 208: thermopw_gen: Configures the thermo_control file for the thermo_pw.x driver. Verifies the prior SCF run status and captures user input for external pressure.

🟣 ZONE 3 | Post-Processor

Focuses on extracting, calculating, and formatting raw output data into physical properties.

• 300: optimized: Refines symmetry (using cell2ibrav) after a vc-relax run, updating lattice parameters and atomic positions for subsequent ground-state runs.
• 301: phonon_proc: Processes raw phonon output data into plottable dispersion curves.
• 302: pdos_proc: Sums and processes Projected Density of States data for plotting.
• 303: optical_proc: Derives optical constants (absorption, reflectivity, refractive index) from QE outputs.
• 304: epc_processor: Analyzes Electron-Phonon Coupling (EPC) data to calculate superconducting parameters like $T_c$.
• 305: thermopw_proc: Scans scf.out from a thermo_pw run. Extracts Voigt-Reuss-Hill averages, Debye temperature, applied strain tensors, and the symmetrized elastic stiffness matrix (in GPa), formatting everything into a clean result.txt file.

🟠 ZONE 4 | Data Visualization

Focuses on rendering graphical representations of the processed data.

• 401: ht_phonon.sh: Bash driver for high-throughput automation of phonon workflows.
• 402: plot-overlay.sh: Gnuplot utility for overlaying multiple datasets (e.g., comparing band structures).
• 403: plot-subplots.sh: Gnuplot utility for generating side-by-side subplot panels (e.g., Bands + DOS).
• 404: bz_plotter: Uses Matplotlib to render an interactive 3D visualization of the Brillouin Zone.
• 405: xrd_plotter: Uses Pymatgen to calculate and plot the theoretical X-Ray Diffraction (XRD) pattern based on the relaxed crystal structure.

🛠️ The utils/ Library (Backend Engines)

These modules operate invisibly in the background, providing core logic to the main Zones.

• config_manager: Manages user-level settings (like saving/fetching the global PSEUDO_LIB_PATH).
• help_manager: Manages the CLI documentation and headless argument flags.
• qe_xml_parser: A robust diagnostic tool that parses Quantum ESPRESSO's data-file-schema.xml. Powers the calculation verification to prevent downstream modules from failing blindly.
• check_strain: Scans thermo_pw logs to extract the precise $3 \times 3$ strain tensors applied to the crystal during elastic calculations.
• symmetric_mat: Reads raw elastic compliances, forces the $6 \times 6$ matrix into strict symmetry ($C_{ij} = C_{ji}$), converts units from kbar to GPa, and formats it for output.

💻 Usage

Interactive Mode: Simply launch the orchestrator to bring up the menu interface:

   qekit.py

📈 Roadmap

v0.4.0: 

1. Upcoming: DFT+U (Hubbard) support with linear response (hp.x) automation.

2. Upcoming: Spin-Orbit Coupling (SOC) and Wannier90 integration.

3. Upcoming: Electron-Phonon suite for EPW code connectivity.

To upgrade to the latest version

pipx upgrade qekit

CITATION:

Farhan Noor, F. QE-Kit [Computer software]. https://github.com/FarhanNoor02/QE-Kit