The different influence of basin hopping temperature between space groups might be due differences in the nature of the energy landscapes (Fig. ). There is a large energy gap between the global minimum and other structures in space group P 2 1 /c, while there is a more uniform distribution of structures in the low energy regions of I4 1 /a and F 2dd. The smaller energy differences in the latter two space groups makes it easier to BH to travel 'uphill' at lower temperatures.