“…The first term (K, if)=(0, 0) gives an equal probability for all shapes of the three-atom triangle, and we can understand that an expansion with this term alone would not give a bound state because of the effect from the repulsive part of the potential. The figure shows contours of the functions (4, 0), (8, 0) and (6,3). The functions (~, 0) all give greatest probability for an equilateral triangle whereas a function such as (6, 3) favours a linear configuration.…”