The field of medicinal chemistry has progressed rapidly in recent decades with the aid of computational tools from quantum chemistry, leading to successful results in the modelling of atoms, molecules, and biochemical systems. This book provides a detailed explanation of how this modelling can be used for the identification and development of novel pharmaceutical compounds. It begins with an overview of quantum physics and an investigation into the propagation of epidemics, before analyzing the mechanisms and potential therapeutic pathways of major tropical diseases-dengue, Zika, Chagas, tuberculosis, and malaria. Further chapters describe the modelling of drugs used in the treatment of other infections, hypertension, and neurological conditions; diagnostic models for autism spectrum disorder; and advancements in the use of nanoparticles as vaccine adjuvants. The book is intended for graduate students and researchers working in biology, physics, chemistry, medicine, pharmacy, and other interdisciplinary fields.