DIRECT SOLUTION OF THE MANY-BODY SCHRODINGER-EQUATION IN THE HYPERSPHERICAL FORMALISM - FORMULATION OF THE CFHH GLF METHOD

To accelerate the convergence of the HH expansion, we modified the HH- GLF method, a new simple hyperspherical harmonic method proposed recen tly by us, into the CFHH-GLF method. Applications of the CFHH-GLF meth od to the three-body systems He and e-e-e+ exhibit very fast convergen ce with number of HH basis sets. With only 36 HH and five GLF, we obta in the ground-state energy of -2.90371 au for He, compared with the ex act value of -2.90372 au, and with only 36 HH and 10 GLF, we obtained the ground-state energy of -0.26188 au for e-e-e+, compared with the e xact value of -0.26200 au. We formulate the CFHH-GLF method in this ar ticle. (C) 1994 John Wiley & Sons, Inc.