Explore the intricacies of molecular interactions in this comprehensive lecture by Alexandre Tkatchenko from the University of Luxembourg, presented at IPAM's Advancing Quantum Mechanics with Mathematics and Statistics Tutorials. Delve into topics such as antisymmetrization, perturbed Hamiltonians, interaction energy, and physical meanings of various molecular phenomena. Examine concepts like induction, polarizability, and dispersion, while addressing challenges in frequency-dependent possibilities. Gain insights into global interaction energy, integration parameters, and linear response in spherical systems. This in-depth presentation, recorded on March 11, 2022, offers a thorough exploration of quantum mechanics applied to molecular theory, suitable for advanced students and researchers in the field.