Siam Quantum 2: An open-source C toolbox for quantum modeling and electronic structure development.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Siam Quantum, an open-source C program developed in Thailand since 2012.
• Originally designed for Hartree-Fock electronic structure calculations.
• Evolved into a modular toolbox for quantum chemistry research and education.

Purpose of the Study:

• Introduce Siam Quantum 2, the next generation of the software.
• Describe its extensible C architecture for method development, readability, and performance.
• Facilitate quantum modeling and electronic structure studies.

Main Methods:

• Density Functional Theory (DFT)
• Second-order Møller-Plesset perturbation theory (MP2)
• Analytic energy gradients
• Molecular geometry optimization
• Quantum molecular dynamics
• Minimum energy crossing point search

Main Results:

• An extensible C architecture for enhanced method development.
• Human-readable Markdown documentation with LaTeX-style equations.
• Improved performance on multi-CPU environments.
• Broadened quantum modeling capabilities.

Conclusions:

• Siam Quantum 2 offers a robust platform for quantum chemistry research and education.
• The software facilitates the bridging of theoretical formulation and source code.
• Demonstrates utility across various quantum modeling and electronic structure studies.