The underlying basis of quantum mechanics is developed in this introduction, with respect for the historical tradition and from a molecular angle. Fundamental concepts in this theory of atomic and molecular structure are discussed, as are the central techniques needed in quantum-chemical applications. Special attention is paid to exposing and clarifying the common ground of Hartree-Fock theory and density-functional theory. An attempt has been made at mathematical simplicity and clarity while avoiding the use of advanced mathematics. Coverage progresses from the rise of atomic theory and the birth of quantum mechanics, to the free particle, diatomic molecules, and wavefunctions and energies. The author teaches chemical physics at the Technical University of Denmark. Annotation c. Book News, Inc., Portland, OR (booknews.com)