MONTE-CARLO OPTIMIZATION OF CORRELATED WAVE-FUNCTIONS FOR NORMAL 2-ELECTRON SYSTEMS

A simple, new type of correlated wave function is proposed for the stu dies of normal two-electron atomic systems: Psi (r(1),r(2)) = Sigma c( m) Phi(m)(r(1),r(2)) with Phi(m)(r(1),r(2)) = exp[-alpha(r(1)+r(2))]/( br(12)+a)(m), where alpha, a, b are non-linear variational parameters. A notable feature of this basis function is that only three terms are required within the framework of the Raleigh-Ritz variational princip le to obtain fairly accurate energy eigenvalues and satisfactory cusp conditions. The nonlinear variational parameters are optimised by usin g the Monte Carlo technique. (C) 1998 Elsevier Science B.V.