The aim of this course is to describe the theoretical foundations of molecular spectroscopy in terms of molecular response properties to static or dynamic electromagnetic fields. As it will not be possible to cover all spectroscopies, a list of topics to detail will be chosen by the students at the beginning of the course. The topics treated will be:
1) light-matter interaction: classical electrodynamics, electromagnetic field Hamiltonian and a brief overview of its quantization. Interaction Hamiltonian.
2) Response properties to static fields: analytical derivatives theory, Coupled-Perturbed Hartree-Fock equations, analytical first and second derivatives of the SCF energy.
3) Response properties to dynamic fields: molecular response function, linear response theory for SCF methods and time-dependent SCF equations.
For each topic, a few specific aspects will be detailed and examples will be discussed consistently with the requests of the students.