On our efforts constructing a proper multireference coupled-cluster method

Abstract

In this paper I summarize our efforts at QTP to construct a proper Multireference Coupled Cluster method. We have not succeeded, however, the popular MR-AQCC method emerged from this project.

Keywords:

• electronic structure theory
• coupled-cluster theory
• multireference methods
• analytic gradients
• MR-AQCC

Acknowledgements

I would like to thank in first place Rod Bartlett for having me at QTP as a postdoc. The work done there was a real team effort and let me thank my fellow postdocs: Jürgen Gauss, John Stanton, John Watts, Leszek Meissner, Stan Kucharski, Marcel Nooijen, Anna Balkova, Hideo Sekino, Maria Barysz, Don Comeau. In Budapest, I acknowledge lots of help and discussions with Péter Surján, Mihály Kállay, and my former student László Füsti-Molnár. My work in Budapest has been supported by the Hungarian Research Foundation through several grants, the last one being F72423.

Notes

Note

1. I call this as a ‘basis state’ since the final wave function is a linear combination of these functions, see Equation (12).