Firefly

Firefly, formerly named PC GAMESS, is an ab initio computational chemistry program for Intel-compatible x86, x86-64 processors based on GAMESS (US) sources. However, it has been mostly rewritten (60-70% of the code), especially in platform-specific parts (memory allocation, disk input/output, network), mathematic functions (e.g., matrix operations), and quantum chemistry methods (such as Hartree–Fock method, Møller–Plesset perturbation theory, and density functional theory). Thus, it is significantly faster than the original GAMESS. Since October 2008, the project is no longer associated with GAMESS (US) and the Firefly rename occurred. Until October 17, 2009, both names could be used, but thereafter, the package should be referred to as Firefly exclusively.