APPROXIMATE SOLUTION FOR ELECTRON CORRELATION THROUGH THE USE OF SCHWINGER PROBES

Quantum energies and two-particle reduced density matrices (2-rdms) ma y be determined without using the N-particle wavefunction by combining the reconstruction of higher rdms from lower rdms and the contracted Schrodinger equation. In this letter we derive a systematic procedure for obtaining reconstruction functionals through the use of Schwinger probes. Previous functionals for the 3 and 4-rdms are generated as wel l as new functionals for higher rdms. Through a quasi-spin model we de monstrate that the 5-rdm, normalized to unity, may be reconstructed fr om lower rdms with the accuracy of its elements ranging from 10(-4) fo r five fermions to 10(-8) for fifty fermions. (C) 1998 Elsevier Scienc e B.V. All rights reserved.