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STO-ns

Created by: Tony Kan
1 devlogs
2h 21m 30s

A lightweight, no-std, pure Rust mathematical kernel for the exact evaluation of two-center Coulomb integrals over ns Slater-type orbitals. Features a zero-allocation, physics-agnostic implementation suitable for both semi-empirical methods (QEq/ReaxFF) and ab initio calculations.

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Tony Kan
Tony Kan worked on STO-ns
about 2 months ago
2h 21m logged

v0.1.0

🚀 Features

  1. Core Mathematical Kernel

    • Exact Evaluation: Implements analytical solutions for two-center Coulomb integrals over $ns$ Slater-Type Orbitals (STOs) using ellipsoidal coordinates.
    • Robust Numerics: Automatically handles singularities (one-center limit $R \to 0$) and numerical instabilities (small $\zeta$ differences) using Taylor expansions.

  2. High-Performance Architecture

    • Zero Allocation: Designed strictly for stack-only memory usage, making it suitable for tight loops and embedded systems.
    • Algorithmic Optimization: Utilizes $O(N)$ recurrence relations for auxiliary integrals and Horner’s method for polynomial evaluation, replacing naive $O(N^2)$ approaches.
    • Compile-Time Computation: Factorials and binomial coefficients are precomputed at compile time to minimize runtime overhead.

  3. Portability & Usability

    • no_std Support: Fully compatible with bare-metal and WASM environments (via libm).
    • Dual API: Offers both a high-level structural API (NsOrbital) for safety and a low-level functional API (sto_coulomb_integral) for raw performance.

New Contributors

  • @TKanX Lead Developer

Full Changelog: https://github.com/TKanX/sto-ns/commits/v0.1.0

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