Preface - American Chemical Society

Downloaded by 80.82.77.83 on April 21, 2018 | https://pubs.acs.org Publication Date: August 14, 2002 | doi: 10.1021/bk-2002-0828.pr001

Preface This book is based on the Accurate Description of Low-Lying Electronic States and Potential Energy Surfaces symposium at the 221 National Meeting of the American Chemical Society (ACS) in San Diego, California from March 30-April 4, 2001. The symposium was organized because of our own interests in this area and because of the many recent developments in methodology for simultaneous treatment of many electronic states across an extended region at comparable levels of accuracy. The availability of such methods underpins developments in other areas such as dynamics and spectroscopy and provides necessary information for understanding phenomena involving electronic excited states. We felt that it was useful to bring together the producers and the consumers of such potential energy surfaces in the hope that each group would provide stimulus to the others. Of the 33 invited speakers and the seven who contributed talks, 17 accepted our invitation to contribute a chapter to this book. These chapters are complemented by three additional chapters from individuals to help develop a more cohesive book as well as an overview chapter. Approximately half of the chapters are focused on the development of ab initio electronic structure methods and consideration of specific challenging molecular systems using electronic structure theory. Some of these chapters document the dramatic developments in the range of applicability of the coupled-cluster method, including enhancements to coupled-cluster wavefunctions based on additional small multireference configuration interaction (MR-CISD) calculations, the method of moments, the similarity transformed equation of motion (STEOM) method, a statespecific multireference coupled-cluster method, and a computationally efficient approximation to variational coupled-cluster theory. The concentration on the coupled-cluster approach is balanced by an approximately equal number of chapters discussing other aspects of modern electronic structure theory. In particular, other methods appropriate for the description of excited electronic states, such as multireference

Hoffmann and Dyall; Low-Lying Potential Energy Surfaces ACS Symposium Series; American Chemical Society: Washington, DC, 2002.

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perturbation theory and time-dependent density functional theory, are not neglected. Although the book has no pretense of being encyclopedic, we intended that the electronic structure sections of the book will provide a poised view of state-of-the-art electronic structure theory. The complementary half considers either structural or dynamical aspects of the coupling of potential surfaces or of regions of potential energy surfaces far from stationary points, and includes chapters on a diversity of methods and applications that illustrate the breadth of the subject, from photodissociation dynamics and molecular resonances in unimolecular decomposition to collisions of vibrationally excited molecules and comparison of quantum scattering and trajectory hopping results for a model system that investigates intersystem-crossing effects. Symmetry properties of adiabatic-to-diabatic transformation matrices and symmetry properties and strategies for efficient evaluation of the spinorbit coupling operator are two more of the diverse set of topics that are covered. Although the focus of the volume is on small molecules, a formulation of semiclassical path integral methods appropriate for studying quantum dynamics in large systems and a chapter on bridging ab initio results and thermodynamic properties of collections of molecules are included. It is our hope that this book will serve as a useful work for advanced graduate students and postdoctoral associates in the field of molecular electronic structure theory and serve as a useful contemporary reference for more established researchers in electronic structure theory, as well as disciplines that directly use potential energy surfaces. In particular, the volume was written with the chemical dynamicist and molecular spectroscopist in mind.

Acknowledgments As with all organizational efforts, the support of many individuals and offices was critical to the successful completion of the symposium and ultimately this book. We acknowledge the Petroleum Research Fund as well as the ACS Division of Physical Chemistry and the ACS Red River Valley Section. Within the University of North Dakota, the Office of Research and Program Development, the Chemistry Department, and particularly, John Ettling, the Vice President of Academic Affairs and Provost, are thanked. We are grateful to Tim Lee


(NASA Ames) and Julia Rice (IBM Almaden) for their confidence and encouragement in organizing the symposium. The staff at the ACS Books Department, especially Kelly Dennis and Stacy VanDerWall in acquisitions and Margaret Brown in editing and production, have been more than helpful in assisting in all phases of the preparation of this book. And, lastly, we thank our wives, Cathy and Gillian, for their support and patience.


Mark R. Hoffmann Chemistry Department University of North Dakota Grand Forks, ND 58202-9024 Phone: (701) 777-2742 Fax: (701) 777-2331 Email: [email protected]

Kenneth G. Dyall Eloret Corporation 690 West Fremont Avenue, Suite 8 Sunnyvale, CA 94087 Email: [email protected]


Preface - American Chemical Society

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