Zintl based superatom P7M2 (M=Li, Na, K & Be, Mg, Ca) clusters with excellent second and third-order nonlinear optical response

Abstract

We report geometric, electronic, and NLO properties of designed zintl superatom P7M2 (M = Li, Na, K & Be, Mg, Ca) clusters in which zintl core P7 is substituted with alkali and alkaline earth metals. The studied superatom clusters show excellent thermal and electronic stabilities and their binding energies pe atom range from −21.54 to −95.93 kcal mol−1. The NBO charge analysis reveals excellent charge separation within the clusters, where the charge is transferred from metals to phosphorus atoms. Furthermore, HOMO-LUMO gaps are significantly reduced which illustrates better electronic properties. The calculated first static hyperpolarizability (βo) and second hyperpolarizability (γo) values are up to 282176 × 10−33 and 30869568 × 10−40 esu, respectively. The variational trend and controlling factors for hyperpolarizability (βo) are also estimated by the two-level model study and the values nicely correlate with each other. The highest βtl value of 185423 × 10−33 esu is obtained for P7Mg2 cluster. The obtained significant NLO response for P7Mg2 and P7Ca2 superatom clusters may be attributed to excess electron character. Moreover, to investigate the nonlinearity from the experimental point of view, we carried out hyper Rayleigh scattering (βHRS) measurement where the highest value of 81340.0 × 10−33 esu, is observed for the P7Ca2 superatom cluster. The excellent NLO responses of these zintl superatoms will pave path for further design and synthesis of even better NLO materials.