• Computational Chemistry
• Computational Spectroscopy
• Theoretical Chemistry
• Response Theory
• CASSCF
• Ab-initio Methods

Computational spectroscopy is an important branch of theoretical chemistry, as it allows one to predict and understand the spectroscopic properties of a molecular system. The main tool for the calculation of spectroscopical observables is response theory, that allows one to predict both the frequency and the intensity of a transition. In this work, I have implemented linear response theory for a complete active space - self-consistent field wavefunction. Particular attention has been devoted to computational efficiency, which is achieved by using the Cholesky deocmposition of the two-electron integrals. Furthermore, I have introduced a completely new numerical procedure to solve the response equations, a generalized eigenvalue problem that needs to be solved iteratively. The solution of response equations at the CASSCF level finally allows the possibility to simulate UV-Visible and Electronic Circular Dichroism spectra of molecules, including ones with a marked multireference character.