Bio molecules are crucial molecular components of biological systems that are responsible for various functions. These functionalities are intimately linked to their conformational preferences. Inositols studied in this book offer simplistic model systems in which theoretical prediction and their experimental validation can be performed easily. The present book uses computational approaches to study the conformation, structure, stability and hydrogen bonding factors of Inositols and dipeptides. This book consists of three chapters. Chapter 1 provides a brief introduction to the theoretical methods used and the molecular systems studied in this book.Chapter 2 provides a short overview of the theoretical methods employed in the current work. A concise explanation of the density functional theory (DFT), moller-plesset perturbation theory (MP2), implicit solvation method (mainly polarizable continuum model (PCM)) and molecular tailoring approach (MTA) techniques are presented here. In Chapter 3 various ab initio calculations using the density-functional (DFT), the second order Moller-Plesset perturbation (MP2) and self-consistent reaction field (SCRF).