Overview

Design concept

VQkit is built around the idea that computational workflows should remain transparent, reproducible, and directly connected to the input and output files produced by the underlying electronic-structure codes.

The toolkit therefore does not introduce a separate proprietary project format. Instead, it works directly with standard VASP and Quantum ESPRESSO files and organizes common preparation and analysis tasks around the active calculation directory.

This design allows users to inspect, modify, archive, reproduce, and reuse their calculations independently of VQkit.

Unified interface

VASP and Quantum ESPRESSO use different input formats, output structures, and workflow conventions. VQkit provides a common interface around these differences wherever practical.

The objective is not to make the two codes identical, but to expose comparable tasks through a consistent workflow while preserving the native requirements of each code.

For example, equivalent workflows can be accessed through similar menu paths even when the files generated or parsed internally are code-specific.

File-based architecture

The active working directory is the central unit of a VQkit session.

VQkit reads files from the selected directory, determines which calculation data are available, generates new input files when required, and writes analysis results back to the working environment.

This file-based approach provides several advantages:

  • No proprietary database is required.

  • Existing VASP and Quantum ESPRESSO projects can be used directly.

  • Generated files can be inspected before calculations are submitted.

  • Output files remain accessible outside VQkit.

  • Workflows can be transferred between local computers and HPC systems.

  • Calculation directories can be archived and reproduced independently.

Modular workflow design

VQkit is organized into independent functional modules rather than one monolithic calculation workflow.

Different modules handle tasks such as structure preparation, input generation, convergence studies, electronic-structure analysis, trajectory analysis, reaction pathways, mechanical properties, and specialized application-oriented calculations.

This modular organization makes it possible to extend individual workflows without redesigning the complete toolkit.

User control

VQkit is intended to assist with computational workflows rather than hide their underlying parameters.

Users retain access to the generated VASP and Quantum ESPRESSO input files and can modify them before calculations are executed.

Similarly, post-processing results are generated from the original calculation outputs so that users can trace the analysis back to the corresponding DFT data.

This approach is intended to balance workflow automation with scientific transparency.

Local and HPC workflows

VQkit can be used to prepare and analyze calculations independently of where the actual DFT calculation is executed.

A typical workflow may therefore involve:

  1. Preparing input files using VQkit.

  2. Transferring the calculation directory to an HPC system.

  3. Running VASP or Quantum ESPRESSO using the available scheduler and computing resources.

  4. Returning to the completed calculation directory.

  5. Running VQkit post-processing on the resulting files.

This separation allows VQkit to remain compatible with different computing environments without imposing a specific job scheduler or cluster configuration.

Extensibility

The internal organization of VQkit is designed so that additional workflows can be incorporated as separate modules.

New functionality can therefore be added for specific calculation types, analysis methods, or application areas while retaining the same general user interface.

This is particularly useful for research software, where new computational methods and analysis requirements frequently emerge during development.

Scope

VQkit acts as a workflow and analysis interface around VASP and Quantum ESPRESSO.

It does not replace the underlying DFT engines and does not perform first-principles calculations independently. The numerical accuracy of a calculation remains determined by the physical model, computational parameters, pseudopotentials, convergence criteria, and settings selected by the researcher.

VQkit is therefore intended to improve workflow consistency and reduce repetitive processing while keeping scientific decisions under the control of the user.