Effect of eliminating various structures

The energy increments from omitting selected basis functions are not additive, thus, using the amormt that the energy is raised by elimination as a measure of the importance of various configurations is not a tmique process, since the result depends upon the order of elimination. Nevertheless, the previous exercise was instructive. 

Although one would not expect a good answer, we show one more calculation with a limited basis - that is the HI5 ionic function by itself. It does not fall in the region plotted in Fig. 2.9, but is shown in Fig. 2.8 where it is marked Ionic . 

2 H2 and localized orbitals Table 2.1. A TZ2P1D basisforH2 calculations. 

---