CALCULATION OF THE GROUND-STATE ENERGY OF A 2-ELECTRON SYSTEM

By the method [1], the ground-state energy of a two-electron neutral atom E = x2 (a.u.) (x = 1.704031775) has been calculated. We estimate the accuracy of the calculation as 1.1 x 10(-8). The quantity x is the eigenvalue of the infinite system of equations. The equations were solved by successive increasing the number of equations N of the corresponding truncated system. The maximum N in [1] was 203; in this work, it is 252. Our calculations for N = 95, 175, 161, and 203 are in complete agreement with [1]. The importance of calculating the levels of a He atom for high-resolution laser spectroscopy where transition frequencies can be measured to a relative accuracy of 10(-12) is emphasized.