TD-DFT based fine-tuning of molecular excitation energies using evolutionary algorithms

An evolutionary de novo design method is presented to fine-tune the excitation energies of molecules calculated using time-dependent density functional theory (TD-DFT). The approach is applied to a pi-conjugated molecular system, azobenzene. The excitation energies for all the molecules generated by the evolutionary design scheme were computed at TD-DFT level on multiple supercomputing clusters. A software developed in-house was used to automatically set up the TD-DFT calculations and exploit the advantages of parallelization and thereby speed up the process of obtaining results for the evolutionary de novo program. Our proposed optimisation scheme is able to propose new azobenzene structures with significant decrease in excitation energies.