This text is a thorough revision of the second edition, which appeared in 1983. The new edition continues to present extensive treatments of quantum principles and methods, atomic and molecular structure, and rotational, vibrational, and electronic spectroscopy. Two new chapters treat the calculation of electronic structure (44 pp) and scattering theory (36 pp, plus new supporting material in the early chapter on linear motion). Also new is a six-page introduction to band theory. A few topics, such as the valence bond method, have been deleted, and the historically based orientation to quantum phenomena has been shortened and moved to the introduction.

The authors, editors, and prepublication reviewers must have devoted a great deal of attention to enhancing clarity. Major and minor revisions throughout the text are so extensive that it is difficult to find even a paragraph that has not undergone some change. The division of chapters into sections has improved markedly. Many of the previous numbered sections have been divided into additional sections. This makes the material clearer and more manageable for the reader and facilitates the matching of assignments to class meetings. In addition, related sections have been clustered into named supersections, each with a paragraph or two of introductory overview. Although some of these paragraphs also appeared in the second edition, their usefulness is much enhanced by the new organization. Improved typography makes equations easier to interpret and remember; fractions are no longer confined to a single line.

Though many chapters cover the same topics as before, some topics have been moved within or between chapters. Presentations of many topics have been extensively rewritten and in some cases augmented. This is especially true of the first three chapters (which treat foundations and basic problems such as barrier penetration and hydrogenic atoms) and the chapter on molecular rotations and vibrations. The chapter on group theory also has useful additions, including two types of figures to illustrate objects belonging to the several point groups.

The foundations of quantum mechanics, previously presented as Chapters 2 and 5, have become Chapter 1. This chapter serves primarily for review and reference, as its pace and mathematical level are too demanding to be an initiation to the subject. Presentations of mathematical formalisms and techniques in later chapters are also rigorous but are accompanied by a greater density of learning aids such as figures, examples, and heuristic arguments. Many of the longer or optional derivations appear in appendices; this helps avoid unnecessary distractions from the main development and gives instructors some choice as to the level of presentation.

The new chapter on calculation of electronic structure is particularly welcome. Other chapters treat the electronic structure of atoms and molecules, much as in the second edition. The new chapter extends considerably the second edition's treatment of Hartree-Fock methods and ab initio methods of treating electron correlation. It also provides brief but useful orientations to basis sets, density functional theory, gradient methods, and semiempirical methods. Although atomic units are widely used in the literature of electronic structure calculations, they receive no systematic treatment anywhere in this book. The bohr and the hartree are introduced ad hoc and in passing, and no Schrödinger equations are expressed in atomic units.

The numerous marginal figures are invaluable and appealing aids to the presentation. Figure 2.27, however, is a jumble, and Figure 9.5 seriously misrepresents the effect of polarization functions on atomic orbitals.

Overall, this edition's important additions and thorough revision have made an outstanding text even better.