There are many fine scripts of quantum chemistry and physicsin print at this time. So the question can be raised as to whywe would write another script, especially one focusing on thesmaller discipline of quantum chemistry. When we began thisproject years ago, we felt that we were a unique juncture inquantum chemistry and technology and that, immodestly, wehad a unique perspective to offer to students. Much of the mainstream of quantum chemistry is now deeplytied to quantum physics, in a cooperative endeavor called"quantum science." At the same time, there is a large, growing,and vital community of people who use the applications ofquantum chemistry to tackle wide-ranging set of problems inthe biological, physical and environmental sciences, engineering,medicine and so on. We thought it was important to bring together, in a singlevolume, a rigorous, detailed perspective on both the "pure" and"applied" aspects of quantum chemistry. As such, one mightfind more detail about any particular subject than one mightlike. We hope this encourages instructors to summarize thescript material and present it in a manner most suitable to aparticular audience. The amount of material contained in thisbook is too much for a one quarter or one semester courseand a bit too little for a yearlong course. Instructors can pickand choose which material seems most suitable for their course. We have attempted to present quantum chemistry and theassociated applications at a level suitable for an advancedundergraduate or beginning graduate student. We haveassumed that a student has prior or concurrent instruction inphysical chemistry or modern physics and has some skills inhandling differential equations. Our sincere effort in this regardwas to spread the solved problems all over this text and thathas a lot to do without belief that the best way to learn is byworking out problems. The thought provoking homeworkproblems are largely examination questions used at variousUniversity. They should be considered to be integral part of thescript as they are intended to illustrate or amplify the mainpoints of each chapter. We have taken some pains to usequantum mechanics in a schematic way, that is, to use theconclusions of such considerations without using or demandinga complete, rigorous, approach. The use of hand-wavingquantum mechanics, we believe, is appropriate for our generalaudience. We summarize, in the appendices, some salientfeatures of quantum mechanics that may be useful for thosestudents with limited backgrounds. Our aim is to convey theblend of theory and experiment as well as that of the essenceof the ideas and the that characterizes nuclear and quantumchemistry. We have included some more advanced material forthose who would like a deeper immersion in the subject. Our hope is that the reader can use this book for anintroductory treatment of the subject of interest and can usethe end-of-chapter bibliography as a guide to more advancedand detailed presentations. We also hope that new and buddingscientists of the future might see this volume as a refreshercourse for sharpening the memory regarding the rudiments ofsomewhat not-so-popular relatively unfamiliar aspects of nuclearand radiochemistry and as an information booth for directionsfor more detailed inquiries.