Assessment of density functional theory approaches to evaluate the first hyperpolarizabilities: The case of molecular switches

The β contrast in molecular switches has been evaluated at different levels of approximation to assess the performance of typical DFT methods, employing GGA, hybrid, and long-range corrected exchange-correlation functionals. It appears that both the BLYP and B3LYP XC functionals behave poorly and either strongly underestimate or overestimate the β contrasts. On the other hand, the performance of the LC-BLYP functional is better, though the improvement over HF is not systematic.