Fig. 1.1 Coordinates for the electronic and the nuclear case for the one-electron atom. r is the coordinate of the electron relative to the nucleus.

Further simplification is obtained by writing R(r) as u(r)=R(r)/r. The radial part of the Schroedinger equation finally becomes:-

where , rest mass of electron.

Which gives the Time Independent Schroedinger Equation solution for spherical symmetry.