By providing detailed explanations of challenging concepts for students and by offering professors an extensive list of subjects, the third edition of this best-selling quantum mechanics text follows the continuing evolution of physics in both esoteric and pragmatic directions. A new chapter, 15, develops the subject of relativistic waves, beginning with a review of basic relativistic concepts and continues with derivation of the Klein-Gordon equation. The chapter delves into the Dirac theory and the Dirac formulation of the four-dimensional spin operator, and concludes with a brief introduction to the covariant formulation of relativistic quantum mechanics. The revision also includes new descriptions and discussions of quantum-well configurations relevant to the quantum dot and the quantum wire and pertinent to semiconductor technology. Employing an assortment of symmetry principles, the transfer matrix method is developed and employed to regain the Kronig-Penny dispersion relation. The discussion of impurity semiconductors has been revised and is accompanied by a new subsection on the p-n junction. A new description of the Hartree-Fock model is included in the revision, which affords a method for obtaining approximate atomic wavefunctions and eigenenergies. This description complements the Thomas-Fermi model, which was new to the second edition. The third edition of Introductory Quantum Mechanics also includes a number of new intriguing problems many of which carry solutions, and a new, informative periodic chart appearing on the inside flap of the front cover. As with his previous editions, Liboff starts with a review of the most relevant elements of classical mechanics and proceeds through two parts that develop quantum theory.