The effect of complexant shape effect on the first hyperpolarizability β0, of alkalides Li+(NH3) 4M- (M=Li, Na, K) was explored. At the MP2/6-311 ++ G level, Li+(NH3)4M- (M=Li, Na, K) have considerable β0 values due to excess electrons from chemical doping and charge transfer. By comparison with the alkalides Li + (calixpyrrole)M-, a complexant shape effect in Li+(NH3)4M- is detected. The β0 values of Li+(NH3)4M - with the "smaller", inorganic, Td-symmetric (NH3)4 complexant are more than four times larger than those of Li+(calixpyrrole)M- with the "larger", organic C4v-symmetric calixpyrrole complexant. The ratios of the β0 values of Li+(NH 3)4M- and Li+(calixpyrrole)M - are 6.57 (M = Li), 6.55 (M = Na), and 5.77 (M = K). In the Li +(NH3)4M- systems, the NBO charge and oscillator strength are found to monotonically depend on the atomic number of the alkali metal anion. The order of the NBO charges of the alkali anions M- is -0.667 (M = Li) > -0.644 (M = Na) > -0.514 (M = K), while the order of the oscillator strengths in the crucial transition is 0.351 (M = Li) < 0.360 (M = Na) < 0.467 (M = K). This indicates that complexant shape effects are strong, and consequently the β0 values of Li +(NH3)4M- are found to be β0 = 70 295 (M = Li) < 96 780 (M = Na) < 185 805 a.u. (M = K). This work reveals that the use of a high-symmetry complexant is an important factor that should be taken into account when enhancing the first hyperpolarizability of alkalides by chemical doping.
|Number of pages||5|
|Publication status||Published - Aug 11 2006|
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry