Abstract
For pt.I see ibid., vol.19, p.149 (1986). The effect of the approximate character of the non-relativistic wavefunction on the second-order relativistic energy correction for the ground state of hydrogen-like atoms is illustrated by means of prototype calculations using Gaussian-type basis functions. Generalisation of the concept of even-tempered basis sets for use in relativistic calculations is proposed. Applications using Gaussian-type and exponential-type functions are presented and the convergence of the second-order relativistic correction with increasing size of basis set is examined. Some attention is paid to the possibility of computation of the third-order energy correction using the first-order correction to the wavefunction.