Open-source PySCF frontend No cluster required Runs offline GPU-ready

Free, open, and
interactive quantum chemistry

QuantUI puts PySCF behind an interactive Jupyter/Voilà UI. Run DFT, MP2, CCSD, CCSD(T), TD-DFT, NMR, geometry optimization, frequencies, and PES scans — visualize structures, orbitals, IR and UV-Vis spectra, all on your laptop with optional NVIDIA GPU offload via gpu4pyscf.

Python 3.9–3.11 · 1500+ tests · MIT License · Linux · macOS · WSL

A complete PySCF workflow

From molecule input to spectra and history replay — everything runs in your local Python kernel.

⚗️
Molecule Input

Paste XYZ, browse an indexed three-tier bundled library (presets + curated + ~1,900 QM9 structures, searchable by name/formula), or run a structure search by name, SMILES, InChI, CID, or CAS — PubChem → NCI CACTUS → an offline bundled-library fallback, so the search still works with no network.

🔬
3D Visualization

py3Dmol-first interactive viewer with a capability-aware backend router. Molecules, optimization trajectories, vibrational modes, and orbital isosurfaces all render inline — and fully offline (3Dmol.js is vendored, never fetched from a CDN). Tunable playback FPS + on-disk cache for instant replay.

Calculations

RHF, UHF, nine DFT functionals, MP2, CCSD, and CCSD(T) — with six calculation types: single point, geometry optimization, frequencies/thermochemistry, TD-DFT UV-Vis, NMR shielding, and 1D PES scans. PCM implicit solvation included.

📊
Spectra & Analysis

IR spectrum (stick + Lorentzian-broadened), UV-Vis plot, orbital energy-level diagram with HOMO/LUMO isosurfaces, and 1H/13C NMR chemical shifts vs TMS. Side-by-side comparison table for multiple calculations.

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Exports & History

Every calc auto-saves to a timestamped directory and replays after a kernel restart. Export structures (XYZ, MOL/SDF, PDB), orbital data (Molden), trajectories (multi-frame XYZ, ASE .traj), cube files, spectra as HTML, full result bundles as .zip, or any run as a standalone .py script.

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GPU Acceleration

Optional NVIDIA GPU offload via gpu4pyscf — RHF, UHF, RKS/UKS DFT, and TD-DFT auto-migrate to GPU when available. Numerical IR-intensity SCFs also offload. Set QUANTUI_DISABLE_GPU=1 to force CPU; the result card always shows which device produced the numbers.

📈
Time Estimator & Calibration

Four-tier calibration suite anchors a per-machine time-prediction model with GPU-vs-CPU partitioning, IQR outlier rejection, and variance-aware confidence labels. Pre-run estimates show in the Calculate tab; predicted-vs-actual accuracy accrues automatically in the analytics dashboard.

⌨️
CLI & Analytics

The quantui CLI inspects the event log (log tail), probes GPU availability (gpu check), and builds a self-contained HTML analytics dashboard (analytics build --open) with GPU-vs-CPU speedup tables, method usage, and estimator-accuracy tracking.

🖥️
Voilà App Mode

Serve the notebook as a polished widget-only UI with voila. Light/Dark themes, inline log viewer, and an in-app bug-report form. Equally at home in a research group or a classroom.

Platform support

PySCF runs natively on Linux and macOS. Windows users have two clear paths.

Platform Status Notes
Linux / macOS Full PySCF installs natively via conda or pip
WSL (Windows) Full Ubuntu WSL environment — follows the Linux path exactly
Windows native Partial UI, structure search, and 3D visualization work; PySCF calculations require the Apptainer container
Windows users: The easiest path is WSL 2 with Ubuntu. Install conda inside WSL and follow the standard installation below. Alternatively, use the Apptainer container which bundles the complete environment in a single file.

Quick installation

Recommended: conda on Linux, macOS, or WSL

bash
# Create a dedicated conda environment
conda create -n quantui python=3.11
conda activate quantui

# Install with PySCF, ASE, and Voilà app server
pip install -e ".[pyscf,ase,app]"

# Launch in JupyterLab (full IDE — shows code)
jupyter lab notebooks/molecule_computations.ipynb

# Or in Voilà app mode (widget-only UI — code hidden)
voila notebooks/molecule_computations.ipynb

Also available via pip install quantui[pyscf,ase,app] or the Apptainer container for Windows.

Step-by-step tutorials

Five guided notebooks — no prior PySCF experience needed. Each runs to completion in under two minutes on a laptop.

# Notebook Topic
01 01_first_calculation.ipynb Your first RHF calculation on water
02 02_basis_set_study.ipynb Comparing STO-3G, 6-31G, and cc-pVDZ basis sets
03 03_multiplicity_radicals.ipynb Open-shell molecules and UHF for radicals
04 04_charged_species.ipynb Ions and charged species
05 05_comparing_results.ipynb Side-by-side result analysis and comparison

Supported calculations

Six calculation types over fourteen methods and nine basis sets, all dispatched through a single Calculate tab.

Calculation type Output
Single Point Energy, HOMO–LUMO gap, Mulliken charges, dipole moment
Geometry Opt Optimized structure with step-by-step trajectory animation
Frequency Vibrational frequencies, ZPVE, IR intensities, thermochemistry (H/S/G at 298 K), animated normal modes
UV-Vis (TD-DFT) Excitation energies, oscillator strengths, UV-Vis spectrum plot
NMR Shielding 1H and 13C chemical shifts vs TMS via GIAO
PES Scan 1D bond/angle/dihedral scan; energy profile + per-step geometries

Fourteen methods, grouped by family:

Family Methods
Hartree–Fock RHF (closed-shell), UHF (open-shell radicals)
Baseline reference; fastest path to convergence
DFT B3LYP, PBE, PBE0, M06-2X, ωB97X-D, CAM-B3LYP, M06-L, HSE06, PBE-D3
Nine functionals spanning hybrid, GGA, meta-hybrid, range-separated, and dispersion-corrected families
Post-HF MP2, CCSD, CCSD(T)
Møller–Plesset (O(N⁵)) for fast post-HF; coupled cluster (O(N⁶) singles+doubles, O(N⁷) with perturbative triples) for benchmark-quality small-molecule energies
Implicit solvent PCM — Water, Ethanol, THF, DMSO, Acetonitrile
Single checkbox; compatible with any method above

Basis sets, from fast to high accuracy:

STO-3G 3-21G 6-31G 6-31G* 6-31G** cc-pVDZ cc-pVTZ def2-SVP def2-TZVP

STO-3G for fast iteration → cc-pVDZ for common research → def2-TZVP for higher accuracy