Electronic Circular Dichroism Spectra Calculation Based on ‎Generalized Energy-Based Fragmentation Approach

Electronic circular dichroism (ECD) spectrum is an important tool for assessing molecular chirality. Traditional methods, like linear response time-dependent density functional theory (LR-TDDFT), predict ECD spectra well for small or medium-sized molecules, but struggle with large systems due to high computational costs, making it a significant challenge to accurately and efficiently predict the ECD properties of complex systems. Within the framework of the generalized energy-based fragmentation (GEBF) method for localized excited states (ESs) calculation, we propose a combination algorithm for calculating rotatory strengths of ESs in condensed phase systems. This algorithm estimates the rotatory strength of the total system by calculating and combining the transition electric and magnetic dipole moments of subsystems. We have used the GEBF method to calculate the ECD properties of chiral drug molecule derivatives, green fluorescent protein, and cyclodextrin derivatives, and compared their results with traditional methods or experimental data. The results show that this method can efficiently and accurately predict the ECD spectra of these systems. Thus, the GEBF method for ECD spectra demonstrates great potential in the chiral analysis of complex systems and chiral material design, promising to become a powerful theoretical tool in chiral chemistry.