Effect of alkaline earth metal atom on the large static first hyperpolarizabilities of alkaline earth-based alkalides Be(NH3)nM (M = Be and Ca) in comparison with alkalides Li(NH3)nNa (n = 1-3)

These alkaline-earth-doped compounds not only present unusual alkaline-earth-based alkalide's features but also exhibit large static first hyperpolarizabilities (β0) up to 125884 au (Be(NH3)3Be) and 112059 au (Be(NH3)2Ca), which constitutes an order of magnitude improvement comparing with the β0 values of the corresponding alkali-doped compounds with alkalide's features (32289 au of Li(NH3)3Na). The alkaline earth metal atom doping is an important and well-performance method to enhance the NLO responses.