This book introduces vibronic coupling density and vibronic coupling
constant analyses as a way to understand molecular structure and
chemical reactions. After quantum study, the behavior of electrons
circulating around nuclei led to the principal concept that underlies
all explanations in chemistry. Many textbooks have given plausible
explanations to clarify molecular structure--for example, the bond
elongation of ethylene under anionization and the nonplanar structure of
ammonia. Frontier molecular orbital concepts were proposed to visualize
the path of chemical reactions, and conventional explanations gave
students a familiarity with molecular structures in terms of the
electronic state. By contrast, this book offers a more rational and more
convincing path to understanding. It starts from the ab initio molecular
Hamiltonian and provides systematic, rational approaches to comprehend
chemical phenomena. In this way, the book leads the reader to a grasp of
the quantitative evaluation of the force applied under the molecular
deformation process. As well, guidelines are offered for integrating the
traditional "hand-waving" approach of chemistry with more rational and
general VCD and VCC alternatives along with the outlook for newly
functionalized chemical systems.