The Dual-Space resolution bias correction in EXPO2010

The limited resolution of experimental diffraction data distorts the Fourier synthesis so that the electron density map obtained by the structure factors is an imperfect representation of the true density: the worse the experimental resolution, the less accurate the Fourier representation. We have recently developed new methods aiming at reducing the resolution effects by correcting it both in the Reciprocal Space (RS) and in the Direct Space (DS): e.g., by modifying the atomic scattering factors in RS and the electron density map in DS. The Dual-Space (DUS) method combines the RS and DS procedures. In addition, new computing strategies have been developed for improving the Fourier map calculation. The DUS algorithm has been introduced in the EXP02010 package in order to obtain more reliable structure models. It has been successfully applied to several test structures. The main features of the new procedure and the results of our applications will be described.