'''Firefly''', formallyformerly known as PC GAMESS, is an [[ab initio quantum chemistry methods|ab initio]] [[computational chemistry]] program for [[Intel]]-compatible [[x86]], [[x86-64]] [[Microprocessor|processor]]s based on [[GAMESS (US)]] sources. However, it has mostly been substantially rewritten (about 60-70% of the code), especially in platform-specific parts ([[memory allocation]], disk [[Output|input-output]], [[computer network|network]]), [[mathematic]] functions (e.g., [[matrix operation]]s), and [[quantum chemistry|quantum chemical]] methods (such as [[Hartree–Fock]], [[Møller–Plesset perturbation theory]], and [[density functional theory]]). Therefore, it is significantly faster than the original GAMESS. The main maintainer of the program is Alex Granovsky. FromSince October 2008, the project is dissociatedno fromlonger associated with [[GAMESS (US)]] and the Firefly name was addedcreated. Up toUntill October 17, 2009, both names willcould be used but thereafter the package willshould be knownreferred solelyto as Firefly exclusively.<ref name="bare_url">[http://classic.chem.msu.su/gran/gamess/ PC GAMESS Home Page]</ref>
As of December 4, 2009, the support of any PC GAMESS versions earlier than the first PC GAMESS/Firefly version 7.1.C is being abandoned (and any and all licenses to use the code are revoked). Therefore, users of the outdated PC GAMESS binaries (version 7.1.B and all earlier releases) are required to discontinue their use of the PC GAMESS and upgrade to Firefly.<ref name="bare_url" />
A state of the art edition of fireflyFirefly has been launched as Firefly v. 8.0.0 RC on July 25, 2012 for public beta testing. A relative comparison has shown that it is much faster and reliable than its previous edition Firefly v. 7.1.G. Many changes have been made to enhance its capabilities and it is expected that it will prove itself a real candidate in the world of Computational Chemistry.
