  A new formula that relates the electron density at the nucleus of
atoms,rho(0,Z), and the atomic number,Z, is proposed. This
formula,rho(0,Z)=a(Z-bZ^(0.5))^3, contains two unknown parameters (a,b) that
are derived using a least square regression to the ab initio derived rho(0,Z)
of Koga dataset from He (Z=2) to Lr (Z=103) atoms (Theor Chim Acta 95, 113
(1997)). In comparison to the well-known formula,rho(0,Z)=aZ^b, used for the
same purpose previously, the resulting new formula is capable of reproducing
the ab initio rho(0,Z) dataset an order of magnitude more precisely without
introducing more regression parameters. This new formula may be used to
transform the equations that relate correlation energy of atoms and rho(0,Z)
into simpler equations just containing the atomic number as a fundamental
property of atoms.
