  Exploratory variational pseudopotential density functional calculations are
performed for the electronic properties of many-electron systems in the 3D
cartesian coordinate grid (CCG). The atom-centered localized gaussian basis
set, electronic density and the two-body potentials are set up in the 3D cubic
box. The classical Hartree potential is calculated accurately and efficiently
through a Fourier convolution technique. As a first step, simple local density
functionals of homogeneous electron gas are used for the exchange-correlation
potential, while Hay-Wadt-type effective core potentials are employed to
eliminate the core electrons. No auxiliary basis set is invoked. Preliminary
illustrative calculations on total energies, individual energy components,
eigenvalues, potential energy curves, ionization energies, atomization energies
of a set of 12 molecules show excellent agreement with the corresponding
reference values of atom-centered grid as well as the grid-free calculation.
Results for 3 atoms are also given. Combination of CCG and the convolution
procedure used for classical Coulomb potential can provide reasonably accurate
and reliable results for many-electron systems.
