|Computational Molecular Spectroscopy|
The book has 670 pages and costs £120.
For ordering information, see http://www.wiley.co.uk or contact the Physical Sciences Department of John Wiley & Sons by emailing email@example.com or by faxing +44 (0) 1243 770154.
PART 1. INTRODUCTION
PART 2. ELECTRONIC STATES
PART 3. ROTATION-VIBRATION STATES
PART 4. ROVIBRONIC STATES AND THE BREAKDOWN OF THE BORN-OPPENHEIMER APPROXIMATION
PART 5. DYNAMICS
To top of page
by Dennis Salahub
Director General, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa.
I had been in my new job as Director General of the Steacie Institute for only a few weeks when Phil Bunker asked me if I would like to write a preface for the new book that Per Jensen and he were editing. I immediately said yes, not only because I guessed this was the sort of thing that DG's did for their team, nor because I was flattered at the invitation (I was), but primarily because I knew, even before seeing the Table of Contents, that Phil and Per would have chosen some of the most difficult, and potentially rewarding, problems in theoretical chemistry and would have found the best authors to portray the state of the art. They have certainly done this.
Their book focuses on three areas: quantum chemistry, bound state calculations and dynamics and is written to foster understanding and interaction amongst these fields. Theoretical chemistry has advanced rapidly in recent years so that now the state of the art draws heavily from all three. True progress requires a mixture of theoretical concepts, computational techniques and, often, raw computing power. Jensen and Bunker's book captures a cross section of these activities. It is aimed at both beginning and seasoned researchers. Newcomers will be able to whet their appetites with a sampling of computational molecular spectroscopy as it now stands; veterans will find enough details, and an extensive bibliography, to satisfy their specialist needs.
Following an introductory chapter by the Editors on the Born-Oppenheimer approximation, the opening chapters focus on the quantum chemical calculation of electronic states and potential energy surfaces. Small molecules are treated by Csaszar, Allen, Yamaguchi and Schaefer, intermolecular interactions by Moszynski, Wormer and van der Avoird. Transition metals are not forgotten (Berces, Zgierski, and Yang) nor are electronically excited states (Buenker, Hirsch, Li, Gu, Alekseyev and Liebermann). Hess and Marian cover relativistic effects and, lest the fixation on the energy become too strong, Sauer gives an overview of properties calculations. Such a varied canvas of applications requires an equally broad palette of computational techniques: CI, CC, SAPT, DFT...
Once one has a sufficiently accurate surface, a very tough problem, one meets a second challenge of equal magnitude: calculating the rotation-vibration states. In this section, Sarka and Demaison guide the reader through perturbation theory, effective hamiltonians and force constants. Tennyson covers variational calculations and Halonen highly excited states and local modes. In attempting to extend ro-vibrational calculations to larger molecules one meets a very steep wall (the 3N-6 catastrophe...) so that more approximate methods are needed. Gerber and Jung show how to do this with a vibrational self-consistent field approach. Even for molecules of relatively modest size, large amplitude, floppy, motion requires special techniques (Makarewicz). The final chapter of this section by Wales treats the complex low-energy motion and tunneling splittings in small water clusters.
The Born-Oppenheimer approximation is the mainstay of quantum chemistry but it sometimes breaks down. The penultimate section of the book treats rovibronic states, rotations, vibrations and electronic motion are coupled and understanding the nature of the various couplings and incorporating them into accurate computational approaches remains a great challenge. Yarkony's chapter deals with adiabatic and nonadiabatic representations for diatomic molecules. Jensen, Osmann and Bunker write on the Renner effect (breaking of symmetry for linear molecules that arises from degeneracy) as does Brown, using an effective Hamiltonian approach. Non-linear molecules in degenerate states also distort and this Jahn-Teller effect is treated, in the presence of spin-orbit coupling, by Barckholtz and Miller. That such intricate and difficult problems as these can now be treated with good accuracy is a testament to the efforts of theoretical chemists, including the authors just mentioned, over the past decades.
One often needs to go beyond eigenstates and worry about the time dependence of molecular (and condensed phase) properties. Indeed, predicting chemical rates on the basis of accurate potential surface calculations (with appropriate non-Born-Oppenheimer corrections when needed) remains the holy grail of theoretical chemistry. The last chapters of the book turn to dynamics. Child writes on semiclassical resonance and wave-packet techniques, Seideman on the superposition of states and Tse and Rousseau provide an entry into very complex systems with a chapter on ab initio (DFT) Molecular Dynamics. These "on-the-fly" dynamics simulations, in which the potential surface is generated from quantum chemistry as needed, have revolutionized simulations in materials and biological modeling.
Jensen and Bunker have, indeed, convinced leading experts over a broad spectrum of theoretical molecular spectroscopy to contribute to this book. The subjects range from fundamental theory to detailed applications, stressing the applications.
The motto of the Steacie Institute is "The fundamental things apply". Per Jensen and Phil Bunker have edited a volume that, while fundamentally fundamental, provides examples of applications and points out avenues to follow for further, more complex, calculations that will ultimately impinge on real practical issues. If there is a current trend towards simulations of staggering complexity, it should not be forgotten that the ultimate value of the computations depends crucially on the approximations made for the energy surfaces, for eigenstates, and for the dynamics per se. I am sure the reader will find such cautionary notes in Jensen and Bunker's book, both explicitly and between the lines, along with a myriad of potential solutions and exciting results.
To top of page
The principal aim of this book is to "bridge the gaps" between traditional quantum chemistry, which is mainly concerned with the calculation of the electronic properties of molecules, theoretical high resolution spectroscopy, traditionally concerned with the calculation of bound rovibronic states, and molecular dynamics which looks at the time dependence of molecular processes. The book is aimed at research workers in all of these fields, and in the border areas between them. The foreword by Dennis Salahub introduces the reader to the 20 chapters that make up this volume.
Editing a book is like a research project. One is eager and enthusiastic at the beginning after one has first developed the idea, one is then often miserable and on the verge of giving up in the middle of the work as unforseen difficulties present themselves, and finally one is happy and relieved when it is completed. During the middle phase one needs constant advice and encouragement. To produce this book we sometimes needed it very much, and thus it is a real pleasure to acknowledge the help given us by Katya Vines of Wiley in this regard. We thank Marion Litz of the Bergische Universität in Wuppertal, Germany, for help with practical matters. It is also necessary to acknowledge the forebearance of the many authors who produced their chapters clearly written in a timely fashion, and then did not complain because of the delays caused by the few who did not.
During the time we worked to produce this book PRB was the holder of an Alexander von Humboldt Senior Award at the Bergische Universität, and he is very grateful for that. Also PJ appreciates the hospitality he received from the Steacie Institute for Molecular Sciences at the National Research Council of Canada in Ottawa. The new Director General of the Steacie Institute for Molecular Sciences, Dennis Salahub, agreed to write a foreword that introduces the chapters, and we thank him for doing such a good job.
Philip R. Bunker
To top of page