GANSU Lite — Quantum Chemistry in Your Browser

A client-side, zero-install quantum-chemistry playground that runs Hartree–Fock, DFT, post-HF, excited-state, gradient and Hessian calculations directly in your browser. Built with TypeScript + Vite, accelerated by WebAssembly (optionally SIMD).

Live demo: https://yasuaki-ito.github.io/GANSU-Lite/

Paper: Y. Ito, H. Fujii, S. Tsuji, K. Nakano, A. Kasagi, "GANSU lite: A zero-install, browser-based quantum chemistry platform," SoftwareX 36, 103046 (2026). doi:10.1016/j.softx.2026.103046

No server, no upload, no install — all computations run locally in JavaScript / WebAssembly.

• SCF: RHF / UHF / ROHF, RKS / UKS / ROKS
• DFT functionals:
  • LDA: SVWN
  • GGA: BLYP, PBE
  • meta-GGA: TPSS (full PKZB correlation)
  • Hybrid: B3LYP, PBE0
  • Range-separated hybrid: CAM-B3LYP, ωB97X-D (RSH-lite, SR-LDA + SR-B88-lite)
• Dispersion: Grimme D2, D3(BJ)-lite (Becke-Johnson rational damping with C8 term)
• Post-HF: MP2, MP3, CCSD (R / U / RO variants)
• Excited states: CIS, ADC(2), TDDFT-TDA, Full Casida (B-coupled RPA)
• Derivatives:
  • Analytic nuclear gradient — RHF / RKS (DFT)
  • Numerical Hessian via analytic gradient + TR-mode projection
  • Vibrational frequencies, IR intensities, thermochemistry
• Geometry optimisation: SD, CG (FR/PR/HS/DY), BFGS, DFP, SR1, GDIIS
• Properties: Mulliken / Löwdin charges, Wiberg bond orders, dipole moment, ⟨S²⟩, energy decomposition, Molden export
• Basis sets: STO-3G, 3-21G, 6-31G, cc-pVDZ, aug-cc-pVDZ, def2-SVP, def2-TZVP
• d/f functions: spherical (5d/7f) or Cartesian (6d/10f). By default each basis set follows its own convention — cc-pVXZ and def2 spherical, Pople and STO sets Cartesian — and the Calculator can override it
• RI-J: automatic for pure DFT (auto-generated or optimised cc-pVxZ-RIFIT auxiliary basis)
• Performance: WebAssembly + SIMD acceleration, Web Worker for non-blocking UI

Every page provides a Theory selector to switch between HF and the DFT functionals listed above.

• Iterative DFT pages (Geom Opt, Freq, PES Scan, Walsh, Basis Set) hide TPSS — its FD-based V_xc is too slow for many SCF runs.
• Basis Set page auto-skips def2-TZVP for DFT (~1 min per basis × molecule).
• Freq Analysis disables ≥4-atom scenarios for DFT (6N grad evals × DFT × big molecule = several minutes).
• PES Scan warns before starting DFT × UHF × ≥15 points.

PySCF cross-check (grid level 5, 17 cases):

The PBE correlation is built on VWN5 as its local part, where the original PBE uses PW92; this is the likely source of the PBE-family offset.

The PySCF reference set is closed-shell only. Spin-polarised correlation is checked separately against an independent implementation of the PBE (1996) and VWN5 formulas, and the TypeScript and WebAssembly kernels are checked against each other on open-shell UKS runs.

Hot paths are compiled to WebAssembly (Rust) with optional SIMD (f64x2). The runtime auto-detects SIMD support and loads the appropriate binary.

The SCF pipeline (including post-HF) runs inside a Web Worker so the UI thread stays responsive.

GANSU Lite is fully client-side. No data is sent anywhere — no analytics, no server-side computation, no tracking. Open the browser DevTools network tab to verify: every calculation runs locally.

This repository contains both the full source and the deployed build.

.
├── index.html, optimize.html, walsh.html, ...   Vite entry points (one per page)
├── src/                    TypeScript sources
│   ├── core/               SCF driver, integrals, DFT (grid + functionals),
│   │                       post-HF (MP2/MP3/CCSD), gradients, Hessian, workers
│   ├── linalg/             eigensolver / linear algebra
│   ├── data/               element data, basis-set tables
│   └── ui/                 page controllers, 3D viewer, charts, i18n, styles
├── wasm-eri/               Rust crate compiled to WebAssembly
│   ├── Cargo.toml / Cargo.lock
│   ├── build-wasm.sh       builds both the plain and the SIMD binary
│   └── src/                ERI (MD/OS/Rys), Fock, MP2/MP3/CCSD, RI,
│                           gradient, Hessian, CPHF, XC integration, Boys
├── public/                 static assets copied verbatim into the build
│   ├── wasm/               pre-built .wasm binaries (committed)
│   ├── basis/              basis-set files (.gbs)
│   ├── xyz/                sample geometries
│   ├── shaders/            WebGPU compute shaders
│   └── tests/              reference values for validation
├── docs/                   >>> BUILD OUTPUT — served by GitHub Pages <<<
├── package.json / package-lock.json
├── tsconfig.json
└── vite.config.ts

docs/ is generated by npm run build and is committed only so that GitHub Pages can serve it (Settings → Pages → Deploy from a branch → main / /docs). Do not edit docs/ by hand — edit src/ and rebuild.

Requirements: Node.js 20+ (tested on 24) and npm. A Rust toolchain is needed only if you want to rebuild the WebAssembly kernels — the pre-built .wasm binaries are committed under public/wasm/.

npm ci            # install exact dependency versions from package-lock.json
npm run dev       # dev server (http://localhost:5173/)
npm run build     # type-check (tsc -b) + bundle (vite build) -> docs/
npm run preview   # serve docs/ locally at http://localhost:4173/GANSU-Lite/

vite.config.ts sets base to /GANSU-Lite/ for production builds (matching the GitHub Pages URL) and / for the dev server. Override with the VITE_BASE environment variable if you deploy under a different path:

VITE_BASE=/ npm run build

rustup target add wasm32-unknown-unknown
cargo install wasm-pack

cd wasm-eri
./build-wasm.sh   # -> ../public/wasm/wasm_eri_bg.wasm  (baseline)
                  # -> ../public/wasm/wasm_eri_simd_bg.wasm  (-C target-feature=+simd128)

The runtime feature-detects SIMD support and loads the appropriate binary. After rebuilding the wasm, re-run npm run build so the new binaries are copied into docs/.

docs/ is the published site. After npm run build, commit the regenerated docs/ together with your source changes and push to main; GitHub Pages picks it up automatically.

If you use GANSU Lite in your work, please cite:

Yasuaki Ito, Haruto Fujii, Satoki Tsuji, Koji Nakano, Akihiko Kasagi. GANSU lite: A zero-install, browser-based quantum chemistry platform. SoftwareX 36, 103046 (2026). https://doi.org/10.1016/j.softx.2026.103046

@article{ITO2026103046,
  title    = {{GANSU lite: A zero-install, browser-based quantum chemistry platform}},
  author   = {Yasuaki Ito and Haruto Fujii and Satoki Tsuji and Koji Nakano and Akihiko Kasagi},
  journal  = {SoftwareX},
  volume   = {36},
  pages    = {103046},
  year     = {2026},
  issn     = {2352-7110},
  doi      = {10.1016/j.softx.2026.103046},
  url      = {https://www.sciencedirect.com/science/article/pii/S2352711026005376},
}

BSD 3-Clause License. See LICENSE.

• Reference values cross-checked against PySCF.
• Auxiliary basis sets (cc-pVxZ-RIFIT) derived from PySCF's bundled Weigend / Hattig basis tables.
• Boys function tables derived from standard quantum-chemistry literature.

GANSU Lite is used in the exercises of a companion textbook: 日本語 · English