page_title: Q-Chem
section_title: History
hierarchical_section_title: Q-Chem / History
caption_attribution_description: English: Advertising postcard for Q-Chem software. This file is licensed under the Creative Commons Attribution 3.0 Unported license. You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
context_page_description: Q-Chem is a general-purpose electronic structure package featuring a variety of established and new methods implemented using innovative algorithms that enable fast calculations of large systems on various computer architectures, from laptops and regular lab workstations to midsize clusters and HPCC, using density functional and wave-function based approaches. It offers an integrated graphical interface and input generator; a large selection of functionals and correlation methods, including methods for electronically excited states and open-shell systems; solvation models; and wave-function analysis tools. In addition to serving the computational chemistry community, Q-Chem also provides a versatile code development platform.
context_section_description: Q-Chem software is maintained and distributed by Q-Chem, Inc., located in Pleasanton, California, USA. It was founded in 1993 as a result of disagreements within the Gaussian company that led to the departure (and subsequent "banning") of John Pople and a number of his students and postdocs (see Gaussian License Controversy).
  The first lines of the Q-Chem code were written by Peter Gill, at that time a postdoc of Pople, during a winter vacation (December 1992) in Australia. Gill was soon joined by Benny Johnson (a Pople graduate student) and Carlos Gonzalez (another Pople postdoc), but the latter left the company shortly thereafter. In mid-1993, Martin Head-Gordon, formerly a Pople student, but at that time on the Berkeley tenure track, joined the growing team of academic developers.
  In preparation for the first commercial release, the company hired Eugene Fleischmann as marketing director and acquired its URL www.q-chem.com in January 1997.  The first commercial product, Q-Chem 1.0, was released in March 1997. Advertising postcards celebrated the release with the proud headline, "Problems which were once impossible are now routine"; however, version 1.0 had many shortcomings, and a wit once remarked that the words "impossible" and "routine" should probably be interchanged! However, vigorous code development continued, and by the following year Q-Chem 1.1 was able to offer most of the basic quantum chemical functionality as well as a growing list of features (the continuous fast multipole method, J-matrix engine, COLD PRISM for integrals, and G96 density functional, for example) that were not available in any other package.
  Following a setback when Johnson left, the company became more decentralized, establishing and cultivating relationships with an ever-increasing circle of research groups in universities around the world. In 1998, Fritz Schaefer accepted an invitation to join the Board of Directors and, early in 1999, as soon as his non-compete agreement with Gaussian had expired, John Pople joined as both a Director and code developer.
  In 2000, Q-Chem established a collaboration with Wavefunction Inc., which led to the incorporation of Q-Chem as the ab initio engine in all subsequent versions of the Spartan package. The Q-Chem Board was expanded in March 2003 with the addition of Anna Krylov and Jing Kong.  In 2012, John Herbert joined the Board and Fritz Schaefer became a Member Emeritus.  In 2018, Evgeny Epifanovsky was named Chief Operations Officer.  The following year, Shirin Faraji joined the Board; Peter Gill, who had been President of Q-Chem since 1988, stepped down; and Anna Krylov became the new president. The active Board of Directors currently consists of Faraji, Gill (past-President), Herbert, Krylov (President), and Hilary Pople (John's daughter). Martin Head-Gordon remains a Scientific Advisor to the Board.
  
  Currently, there are thousands of Q-Chem licenses in use, and Q-Chem's user base is expanding, as illustrated by citation records for releases 2.0, 3.0, and 4.0, which reached 400 per year in 2016 (see Figure 2). 
    As part of the IBM World Community Grid, about 350,000 Q-Chem calculations are performed every day by the Harvard Clean Energy Project, which is powered by Q-Chem.
  Innovative algorithms and new approaches to electronic structure have been enabling cutting-edge scientific discoveries. This transition, from in-house code to major electronic structure engine, has become possible due to contributions from numerous scientific collaborators; the Q-Chem business model encourages broad developer participation.  Q-Chem defines its genre as open-teamware: its source code is open to a large group of developers. In addition, some Q-Chem modules are distributed as open source.  Since 1992, over 400 man- (and woman-) years have been devoted to code development. Q-Chem 5.2.2, released in December 2019, consists of 7.5 million lines of code, which includes contributions by more than 300 active developers (current estimate is 312). See Figure 3.
caption: Postcard advertising the release of Q-Chem 1.0.
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