Effects of incorrect phases on difference density distributions

The effect of incorrect phases on difference density distributions is illustrated with the example of thiourea (space group P2₁ma). Two difference density maps with phases from the free-atom model (R = 0.030) and a molecular model of the charge distribution (R = 0.017) are calculated. These maps show deviations as large as 0.2 e Å^-3 in the peak heights.