Returns Le Roy radius for initial pair-state.

Le Roy radius 1 is defined as $$2(\langle r_1^2 \rangle^{1/2} + \langle r_2^2 \rangle^{1/2})$$, where $$r_1$$ and $$r_2$$ are electron coordinates for the first and the second atom in the initial pair-state. Below this radius, calculations are not valid since electron wavefunctions start to overlap.

Returns

LeRoy radius measured in $$\mu m$$

Return type

float

References

1

R.J. Le Roy, Can. J. Phys. 52, 246 (1974) http://www.nrcresearchpress.com/doi/abs/10.1139/p74-035