The study of quantum mechanics and its application occupies ia central position in the physical sciences, forming the basis for an understanding of atomic, molecular, nuclear, particle and condensed matter physics. The purpose of this book is to provide a core text in quantum mechanics for students of physics at the undergraduate level. It gives a modern, comprehensive introduction to the principles of quantum mechanics, to the main approximation methods and to the application of quantum theory to a wide variety of systems. The needs of students having an average mathematical ability are kept very much in mind, with the avoidance of complex mathematical arguments and any compression of material. The text is illuminated throughout by careful explanation and physical insight. Problems sets, which cover all the main topics, reinforce the student's understanding and act as a progress. A solutions manual is available for the use of teachers. Features: Comprehensive coverage of core material in quantum mechanics; Full and detailed explanations to help students of average mathematical ability; Additional topics covered in this edition include Feynman's path integral, the Berry phase, quantum jumps and Bose-Einstein condensation; New chapter on relativistic quantum mechanics; Problem sets to help students to monitor their progress and increase understanding. Quantum Mechanics is a self-contained text, suitable for both one and two year, or semester, courses.