Ab Initio Methods are computational techniques used in quantum chemistry to predict molecular properties and behaviors from first principles, without empirical parameters. These methods rely on fundamental physical laws, particularly the Schrödinger equation, to calculate the electronic structure of atoms and molecules. These methods include various approaches, such as Hartree-Fock and Density Functional Theory (DFT), which help scientists understand chemical reactions, molecular interactions, and material properties. Ab initio methods are essential for researchers in fields like materials science, pharmacology, and nanotechnology, providing insights that guide experimental work and theoretical studies.