Surface-enhanced vibrational raman optical activity: A time-dependent density functional theory approach

In this work we present the ?rst simulations of the surface-enhanced Raman optical activity (SEROA) using time-dependent density functional theory (TDDFT). A consistent treatment of both the chemical and electromagnetic enhancements is achieved by employing a recently developed approach based on a short-time approximation for the Raman and ROA cross-sections. As an initial application we study a model system consisting of adenine interacting with a Ag20 cluster. Because both the silver cluster and adenine in the absorption geometry are achiral, the chiroptical properties are due to the interactions between the two systems. Our results show that the total enhancement is on the order of 104 both for SEROA and SERS. However, the chemical enhancement is found to be larger for SEROA than for SERS. The results presented here show that SEROA can be a useful approach for studying induced chirality in small metal clusters due to the absorption of molecules.