OFFSET
1,2
COMMENTS
The wave function of the 1s orbital of the hydrogen atom is psi(r)=exp(-r/a0)/(sqrt(Pi*a0^3)) where a0 is the Bohr radius A003671. The radial distribution function is psi^2(r)*4*Pi*r^2 which then simplifies to 4*r^2*exp(-2r/a0)/a0^3. Integrating from 0 to infinity and finding the value R where the value inside is the same as outside yields a0 times the root of 2 + 4R + 4R^2 = e^(2R).
LINKS
EXAMPLE
1.33703015686178015895672863229584749481139389751391113904385940906878277458....
MATHEMATICA
RealDigits[r /. FindRoot[2 + 4*r + 4*r^2 - Exp[2*r] == 0, {r, 3/2}, WorkingPrecision -> 100], 10, 87][[1]] (* Amiram Eldar, Aug 28 2020 *)
PROG
(PARI) solve(r=1, 2, 2+4*r+4*r^2-exp(2*r))
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Charles R Greathouse IV, Jun 19 2020
STATUS
approved