Projects / Siam Quantum

Siam Quantum

Siam Quantum (SQ) is a quantum chemistry program that calculates wave function and total energy of molecules. It currently supports restricted and unrestricted Hartree-Fock method using Gaussian-type basis functions. The source code is well documented because it was initially designed for academic purposes so that students can easily understand. However, Siam Quantum can also produce high quality results for research purposes because the energies calculated are comparable to the ones produced by other software packages such as Gaussian or GAMESS, with the errors in the order of 10^-6 Hartrees, which can be further reduced with more strict cut-off.

Tags	Quantum Mechanics Quantum Chemistry
Licenses	GPL
Operating Systems	Linux Windows
Implementation	C
Translations	English Thai

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Recent releases

1.2.4

07 Jun 2011 12:17

Release Notes: This minor performance improvement release stores integration results in memory in order to be reused in the next iterative cycle instead of re-calculating them. DIIS method has been implemented, allowing the iterations to converge to a solution faster.

1.2.3

23 Oct 2010 05:36

Release Notes: Geometry optimization and population analysis are now available. The calculation of forces acting on nuclei within a molecule was implemented, which makes it possible to predict the three dimensional structure of the molecule using only a fundamental equation of quantum mechanics, the Schrödinger equation.

1.2.2

07 Oct 2010 22:23

Release Notes: This major bugfix and performance improvement release is four times faster, has better convergence behavior, and can interface with visualization software such as Gabedit. The enhanced speed is due to the use of a density matrix to help pre-screen 2-electron integrals, and better handling of memory usage.

1.2.0

12 Jul 2010 08:24

Release Notes: Unrestricted Hartree-Fock calculation was added, which makes it possible to theoretically study an open-shell system such as triplet oxygen molecule.

1.1.0

18 Mar 2010 22:03

Release Notes: Minor improvements and bugfixes. Siam Quantum (SQ) runs much faster using a well-known technique whereby the 2-electron integrals have been grouped into "shell". It is now feasible for SQ to perform calculations on buckyball (C60). Many parameters can now be controlled using command-line options. A bug regarding the xyz format is now fixed.