Dear all, I have got a solution from MR. It consists of 4 independent molecules. It accounts for half of the contents of the ASU. The resolution is 2.5 A. I am trying averaging with DM. I have generated a NCS mask including just one molecule. The correlation coefficients of the ncs operators rose from 0.54 to 0.85 on 40 cycles, however, the map is much worse than the original one. I used F, PHI_C and FOM from refmac. What could be wrong? Armando