Solving the Schrodinger equation for helium atom and its isoelectronic ions with the free iterative complement interaction (ICI) method

The Schrodinger equation was solved very accurately for helium atom and its isoelectronic ions (Z=1-10) with the free iterative complement interaction (ICI) method followed by the variational principle. We obtained highly accurate wave functions and energies of helium atom and its isoelectronic ions. For helium, the calculated energy was -2.903 724 377 034 119 598 311 159 245 194 404 446 696 905 37 a.u., correct over 40 digit accuracy, and for H-, it was -0.527 751 016 544 377 196 590 814 566 747 511 383 045 02 a.u. These results prove numerically that with the free ICI method, we can calculate the solutions of the Schrodinger equation as accurately as one desires. We examined several types of scaling function g and initial function psi(0) of the free ICI method. The performance was good when logarithm functions were used in the initial function because the logarithm function is physically essential for three-particle collision area. The best performance was obtained when we introduce a new logarithm function containing not only r(1) and r(2) but also r(12) in the same logarithm function. (c) 2007 American Institute of Physics.