Density Functional Theory (DFT) is currently receiving a great deal of attention as chemists come to realize its important role as a tool for chemistry. This book covers the theoretical principles of DFT, and details its application to several contemporary problems. All current techniques are covered, many are critically assessed, and some proposals for the future are reviewed. The book demonstrates that DFT is a practical solution to the problems standard <IT>ab initio</IT> methods have with chemical accuracy.<P>The book is aimed at both the theoretical chemist and the experimentalist who want to relate their experiments to the governing theory. It will prove a useful and enduring reference work.