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Endeavour Features: Structure Solution Wizard

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

Endeavour Features Overview...
Next: Space-group Determination...

Step 1 of 8: Define cell parameters and space-group Step 1 of 8:
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 of 8: Define molecules (optional)

Step 2 of 8:
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. Molecules can be fixed at certain positions and may rotate along a reference atom.

Step 3 of 8: Define atoms in unit cell

Step 3 of 8:
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 of 8: Define the diffraction data

Step 4 of 8:
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 8: Define the diffraction data Step 5 of 8:
Choose between automatic and manual structure solution settings

Since version 1.6 all structure solution calculation parameters can be adjusted automatically after cell parameters, space group, molecules, single atoms, as well as diffraction data have been entered. This is the default and recommended setting, and you are led to the final page of the wizard. (In this example we continue with the next page.)
Step 6 of 8: Define settings for potential

Step 6 of 8:
Define settings for potential

This page is dedicated to the input of data needed for the calculation of the potential energy. There are three possible functions that may be used, two of them - the 'simple repulsion potential' and the 'Lennard-Jones potential' - need empirical parameters. The "Hofmann potential", introduced in version 1.3, enables much easier solution of crystal structures of rigid molecules and is even capable of predicting the crystal structures of rigid molecules without using any powder diffraction data. So it does not contain any parameters that have to be adjusted by the user, making its usage extremely simple. Concerning the other two potentials, Endeavour has been designed carefully to especially make the generation of potential parameters as simple as possible.

Step 7 of 8: Define optimization settings

Step 7 of 8: 
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 Step 8 of 8:
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.

Since version 1.5, you can check out several more parameters through the "Advanced settings for structure solution" dialog, which is available from the final page of the structure solution wizard. For example, you can treat molecules as flexible rather than rigid-body molecules.

Advanced settings dialog

Endeavour Features Overview...
Next: Space-group Determination...