CRYSTAL IMPACT Homepage DIAMOND - Visual Crystal Structure Information System ENDEAVOUR - Structure Solution from Powder Diffraction MATCH! - Phase Identification from Powder Diffraction


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Structure Solution Wizard

This page introduces ENDEAVOUR's so-called 'Structure Solution Wizard' for the easy preparation of the structure solution process:

Step 1 of 7 - Define cell parameters and space group
Cell parameters must be known, i.e. the powder data must be indexed, whereas the knowledge of the correct space group is not essential. The calculation can always be performed in P1 and the correct space group can be determined afterwards. However, if the space group is known, the calculation speed is much higher.

Step 2 - Define cell parameters and space group
Step 3 - Define rigid body molecules

Step 2 of 7 - Define molecules (optional)
Endeavour supports the usage of molecules with flexible torsion angles as well as rigid-body fragments if they do not lie on special positions of the spacegroup.

Step 3 of 7 - Define atoms in unit cell
Enter the unit cell contents, i.e. the formula sum and the number of formula units per unit cell for single atoms, i.e. atoms which do not belong to molecules.

Step 4 - Define atoms in unit cell
Step 5 - Define settings for potential

Step 4 of 7 - Define the diffraction data
The next wizard page is dedicated to the input of the diffraction data. You can open the prepared file containing the diffraction data as a list of 2 theta- and corresponding intensity values, or, as in this case, a list of |F|(hkl) data.

Step 5 of 7 - Define settings for potential
This page is dedicated to the input of data needed for the calculation of the potential energy. There are two possible funtions which may be used, the 'simple repulsion potential' and the 'Lennard-Jones potential'. Both potentials need empirical parameters. Endeavour has been designed carefully to especially make the generation of potential parameters as simple as possible.

Step 1 - Define the diffraction data
Step 6 - Define optimization settings

Step 6 of 7 - Define optimization settings
This page offers some options concerning the optimization. For instance, the so-called 'cost function balance' may be adjusted, i.e. the contribution of either of the two parts of the cost function to the overall value. Thus, weak diffraction data may to a certain degree be balanced by a high quality potential and vice versa.
Besides this, the speed of the calculation is controlled by the slider 'optimization speed' that could take any integer value from 1 to 10. A value of 10 means highest optimization speed, however, because of the underlying simulated annealing optimization method, also lowest success probability.

Step 7 of 7 - Define environment settings
Since Endeavour is not only a program for structure solution but also for structure visualization, you can view the intermediate structures during the structure solution process. On wizard page 7 you can tell the program how this should be done.

Step 7 - Define environment settings