Energy Landscapes: With Applications to Clusters, Biomolecules and Glasses David J. Wales Cambridge U. Press, New York, 2004. $90.00 (681 pp.). ISBN 0-521-81415-4
The quest for new lands and landscapes has always been a pursuit of inquiry born out of curiosity and adventure, but also out of anticipated gains. Mapping out landscapes—recently, even beyond the planet Earth—and putting them on the map, literally and figuratively, is an essential element of that pursuit. David J. Wales’s Energy Landscapes: With Applications to Clusters, Biomolecules and Glasses takes us on a journey of discovery and exploration of a different type of terrain—energy landscapes of systems larger than just a few atoms. It is the first textbook on this subject.
Although more nebulous, at least in the eyes of nonspecialists, energy landscapes present an expert explorer—physicist, chemist, or biologist—with the same type of features (valleys, ridges, peaks, and passages) as their planetary cousins. Why would one want to know the peculiarities of the energy landscapes of different physical, chemical, and biological systems? Because in an analysis performed at the atomic or molecular level, the energy landscapes are the ultimate reason for the structural forms these systems can assume and the complex transformations, including chemical reactions, they can undergo. Another central role of energy landscapes is to furnish a common language for describing a broad variety of seemingly disparate systems and phenomena and for identifying common, even universal, elements in them.
In most cases, the topographies of energy landscapes are much more complex than the ones we experience in our hiking and climbing expeditions. The reason is that the potential energy surface of an N-atom system is embedded in a space whose dimensionality scales as 3N. Devising tools, which are appropriate and efficient for the exploration and mapping of these multidimensional surfaces, is a challenge that demands ingenuity and is the focus of ongoing efforts by many experts. Wales’s book gives an account of the state of the art in this area. It describes, even if only tersely, the various techniques used to locate minima and saddle points and presents a fairly detailed discussion of how the knowledge of these can be synthesized into a distilled but representative and informative picture of a complex energy landscape (for example, in the form of disconnectivity graphs).
Energy Landscapes also offers readers a survey of dynamical and statistical mechanical techniques for exploration of structural transformations and thermal properties as defined by the features of the underlying potential or free energy surfaces. Applications and illustrations are given for three types of systems: clusters, biomolecules, and glasses.
The first three chapters are aimed at those who are at the beginning of the road. As an introduction to the main subject, they sketch methods used to compute potential energy surfaces, introduce issues relevant to systems discussed later, review the essence of the Born–Oppenheimer approximation and the normal modes, and present an overview of the role of symmetry. The seven chapters that follow focus on the central subject of energy landscapes and their applications and discuss a variety of other issues, including those of general conceptual and methodological nature. Among the latter are phases and phase changes in finite systems, and scaling laws.
The book is theoretical, with some mention of the relevant key experimental findings. Its scope is extensive; as a consequence, not all the subjects are covered with equal detail. Some associated issues—for example, fitting potential energy surfaces and the effect of rotation on potential energy landscapes—are not touched upon at all. The author might consider including these topics in the second edition. The balance between the formal mathematical and descriptive parts is about right for the intended broad readership, from graduate students to experts. The main value of the book lies in its being a rich resource that captures the current status of its subject matter. The style and presentation are engaging and the excellent illustrations, many in beautiful color, only heighten curiosity and enhance the desire to read on. The extensive lists of references at the end of each chapter will lead the inquiring reader to the original literature.
Energy Landscapes will be invaluable, as a roadmap and guide, to both novices and the seasoned in the expanding group of explorers of energy landscapes. University professors will find it most useful in introducing the subject to their students.
