A Density Functional Approach to High Harmonic Generation

The role of the asymptotic behavior of the ground state exchange-correlation (xc) potential is examined for the case of high harmonic generation (HHG) in N$_2$ via Time-dependent Density Functional Theory (TDDFT) within the adiabatic approximation. High harmonic generation (HHG) is a high-energy phenomenon that has been theoretically investigated using the strong- field approximation (SFA) within the single active electron approximation (SAEA) for small molecules. In the case of N2, experimental results for characteristic features of the harmonic emission suggest a breakdown of those approximations. TDDFT bypasses the need for such approximations as it accounts for all the electrons in the system; however, it requires approximations to the xc-potential. We investigate how asymptotic corrections to the Local Density Approximation (LDA) xc-potential influence the HHG spectrum.