Electron density functions for simple molecules

Trial electron density functions have some conceptual and computational advantages over wave functions. The properties of some simple density functions for H(+) (2) and H(2) are examined. It appears that for a diatomic molecule a good density function would be given by rho = N(A(2) + B(2)), in which A and B are short sums of s, p, d, etc. orbitals centered on each nucleus. Some examples are also given for electron densities that are appropriate for excited states.