UTILIZATION OF DEFORMATIONS IN MOLECULAR QUANTUM-CHEMISTRY AND APPLICATION TO DENSITY-FUNCTIONAL THEORY

The aim of this article is to present in a way accessible to most quan tum chemists a general mathematical method which consists in deforming wave functions and density functions (in the spirit of the local scal ing transformation). This deformation method allows us to obtain sever al new results, including a characterization of the set of wave functi ons that have the same given density function (which gives a new insig ht on a result of G. Zumbach and K. Maschke, Phys. Rev. A 28, 544 (198 3)) and an N-representability result where symmetry is taken into acco unt. We also propose new theoretical ways to generate approximations o f the exact density functional and give a numerical example. (C) 1998 John Wiley & Sons, Inc.