• computational
• MCD
• vibrational resolved
• vibronic

The purpose of this work was to develop a computational protocol for the simulation of Magnetic Circular Dichroism (MCD), also including the vibrational contributions.
The standard theoretical formulation of MCD relies on quantities, such as excited-to-excited transition moments, which are rarely available in standard quantum chemical software.
The few implementations in general-purpose programs are either for electronic structure methods poorly suited to handled medium-larg molecular systems, or have limited support, being potential unstable or lacking for instance models to simulate solvent effects, or density functional theory (DFT) exchange-correlation functionals.
Since the modification of large existing codes is particularly complex, in order to investigate the impact of the vibrational information on the MCD intensity, it was decided to prioritize specialized, open codes, which would be rather compact could be tailored if needed.
The one chosen here derives from the ``Sum-Over-States'' (SOS) formalism.
It is relatively intuitive and, despite its inherent approximations, showed good performance compared to more accurate, but also complex, models.
The relative simplicity of the theory makes it easier to implement outside electronic structure calculation programs and does not require a long development process.
The inclusion of the vibronic effect in the evaluation of the properties considering also the Herzberg-Teller contribution is focal in this study.