Siam Quantum (SQ)

is an ab initio quantum chemistry program that uses quantum mechanics to determine the total energy and wave function of molecules within the framework of Hartee-Fock and MP2 method.


  • March 22, 2013 - Siam Quantum version 1.2.8 is a major feature enhancement release. The Minimum Energy Crossing Point (MECP) can now be calculated
  • March 10, 2013 - Major speed enhancement version 1.2.6 has arrived. MP2 mode is fast and requires small storage. The speed enhancement is achieved by multipole approximations of the electron integral and parallel run supports for HF, OPT, and, MP2 modes.
  • Dec, 1, 2012 - Major feature enhancement and bug fix version 1.2.5 is finally here. Moller-Plesset Perturbation Theory (MP2) is now available.
  • June 5, 2011 - Speed enhancement version 1.2.4 is now available.
  • October 22, 2010 - Major feature enhancement version 1.2.3 is here. After two years of hard work, Mr. Theerapon Khamla has successfully implemented geometry optimization for Siam Quantum. See download section for details
  • Errata! - Energy of Nitrogen Molecule - (FIXED)
  • October 7, 2010 - Major bug fix and performance improvement version 1.2.2 is here. See download section for details
  • August 15, 2010 - Minor bug fix version 1.2.1 is here. See download section for details
  • Errata! - Energy of Nitrogen Molecule - (FIXED)
  • July 12, 2010 - Version 1.2.0 is here. Unrestricted Hartree-Fock is now available. See download section for details
  • March 19, 2010 - FAQ added in the documentation section
  • March 18, 2010 - Version 1.1.0 is here. Much faster! See download section for calculation on buckyball (C60) and further details


  • develop source code and documentation originally for academic purposes in order to introduce Thai students to the field of electronic structure calculations
  • calculate Hartree-Fock and restricted MP2 energies of molecules with the results comparable to the standard quantum chemistry software such as Gaussian and GAMESS
  • perform post SCF calculations such as electron density or molecular orbitals
  • Geometry optimization and simple population analysis
  • Minimum Energy Crossing Point (MECP)
  • is free (GPL License), support both Linux and Windows

* The figure shows geometry optimization calculation by Siam Quantum


  • Quantum Molecular Dynamics
  • Unrestricted MP2 energy and gradient


  • Density Functional Theory (DFT)
  • Spectroscopic parameter prediction
  • Support periodic system such crystal and carbon nanotube, especially at MP2 level
  • Support parallel calculation on Linux cluster
  • Graphic User Interface (GUI)
  • a book on electronic structure theory (in Thai language)
Syndicate content