Introduction to proceedings of Molecular Quantum Mechanics 2013: electron correlation: the many-body problem at the heart of chemistry

This special issue of Molecular Physics is associated with an international conference, Molecular Quantum Mechanics 2013, which was held in the city of Lugano, Switzerland, at the Lugano Conference Center, from 2–7 June 2013. The conference involved more than 320 participants, representing 33 countries. The conference schedule accommodated 3 historical lectures, 32 plenary lectures, 28 contributed talks selected from the abstracts submitted, and 2 very strong poster sessions containing 200 contributed posters.

The meeting was generously supported by ETH Zurich, the Johannes Gutenberg University of Mainz, the University of Italian Speaking Switzerland (USI), the Ticino Department of Education, the Swiss Science Foundation, the Swiss Chemical Society, as well as industrial sponsorships from IT companies (IBM, Hewlett-Packard, RIKEN-Fujitsu, Dell), publishers (ACS: Journal of Chemical Theory and Computation, Wiley: Journal of Computational Chemistry and WIREs, Taylor and Francis: Molecular Physics), as well from the chemical/pharmaceutical industry (Bayer, Dow, as well as BASF, Merck-Serono, Novartis, Roche, Syngenta). The local organisation and administration were handled by Hans Peter Lüthi and Christine Siegrist (ETH), Nicole Birkle (Mainz), Albino Zgraggen, and Daniela Wirz (USI). The scientific co-organisers all gratefully acknowledge Hans Peter Lüthi's outstanding efforts that allowed the conference to run so well. In addition, we acknowledge the Franklin College in Lugano for making affordable housing available to the conference participants.

MQM 2013 recognised the work of Prof. Rodney J. Bartlett of Quantum Theory Project, at the University of Florida. Prof. Bartlett's scientific accomplishments centre on advances in electron correlation methods, particularly coupled cluster theory. It is for this reason that the electron correlation problem represented the central scientific theme of the conference. The Special Issue opens with a biography of Prof. Bartlett, written by Prof. John Stanton [1]. Readers may also be interested in an earlier Special Issue in honour of Prof. Bartlett, published in 2005, to coincide with his 60th birthday [2], as well as reviews on coupled cluster theory [3], and his ab initio density functional theory approach [4] that Prof. Bartlett published as part of a Special Issue on the 50th anniversary of the Quantum Theory Project [5], which he co-edited.

During the 5-day meeting, which gathered many of the leaders in the field, a number of remarkable new results and ideas were reported. Consistent with the theme of the conference, a number of exciting approaches to strong correlations were discussed, as well as new approaches for treating dynamic correlation at quantitative accuracy, for molecules in both ground and excited states. Several of these presentations were from young scientists, who were given an excellent platform to introduce their research to the community. The presentations showed that method development in computational quantum chemistry allows us to treat molecular systems at an unprecedented accuracy. In addition, the step towards a new length scale involving very complex systems (enzymatic reactions, materials) is being completed, by advances in electronic structure algorithms, and new ways to focus on an active site, including improvements in quantum mechanics/molecular mechanics (QM/MM) methods as well as novel approaches to embedding and effective Hamiltonians.

Four previous conferences in the Molecular Quantum Mechanics series can also be found in Molecular Physics, including Berkeley 2010 in honour of Prof. Fritz Schaefer [6], Budapest 2007 in honour of Prof. Peter Pulay [7] (see Vol. 105, issues 19–22), Cambridge 2004 in honour of Prof. Nicholas Handy [8] (see Vol. 102, issues 23–24, and Vol. 103, issues 2–3 and 6–8), and Seattle 2001 in honour of Prof. Ernest Davidson [9] (see Vol. 100, issues 3–4, 6, 11).

Finally, looking to the future, the next conference in the MQM series is planned for 26 June to 1 July 2016, in Uppsala, Sweden, to be organised by Roland Lindh, and will honour the scientific contributions of Per Siegbahn, and the memory of both Per-Olov Lowdin (born in 1916) and Bjorn Roos.