A 3-DIMENSIONAL FINITE-ELEMENT APPROACH TOWARDS MOLECULAR SCF COMPUTATIONS

Fully three-dimensional, SCF ground-state computations for the Hartree equation are carried out by a finite element approach that completely avoids forming or storing the Fock matrix. A combination of strategies is used to reduce storage and computational requirements by orders of magnitude over the traditional finite element approach, which makes three-dimensional molecular orbital computations feasible. Results using the three-dimensional formulation and computer program are shown for one-electron systems: He+ and H-2+, and for two-electron systems: He and H-2. The best results are within about 30-100 micro-Hartrees of the exact values of the total energies for the ground states of these systems, indicating that our three-dimensional approach has been correctly implemented in the computer code.