When Simulated Annealing fails

Parent Previous Next

When Simulated Annealing fails

       If Simulated Annealing fails:

1) The quality of data is not good and the diffraction pattern is not suitable for the extraction of integrated intensities. In this case can be convenient to perform the optimization by using the cost function R weighted profile.

2) Starting model is incorrect: bond distances and angles are not entirely accurate, the number of building blocks is wrong. Improve your model with Cambridge Structural Database (CSD) or building packages (Avogadro, ChemSketch, ChemDraw, ...), check for atom in the output file (about 15-20 Ang/atom).

3) The assumption about thermal factors are invalid. Check thermal factors from similar structures.

4) Space group and cell are not correct. Additionally, in many cases it may be necessary to carry out a series of independent calculations to test different potential space groups and/or unit cell choices.

5) For complex structure the default SA conditions can be not sufficient. Try with slower temperature reduction, increase the number of moves and/or runs.

Created with the Personal Edition of HelpNDoc: Full featured Documentation generator