Chapter 11 – HOW TO - Solutions
Most How-Do's below will refer back to appropriate sections in this document in order to
avoid too much repetition.
11.1 - How to Run Structure Validation with PLATON
11.2 - How to do an Exhaustive Geometry Calculation and Listing
−
Terminal window instruction:
platon -c name.cif . The result is in
name.lis &
name.lps.
−
Terminal window instruction:
platon name.cif. Click in main menu 'CALC ALL'.
The result is in
name.lis &
name.lps.
See
Appendix-VI for an explanation of the content of the listing file
11.3 - How to Prepare a default ORTEP plot
−
Terminal window instruction:
platon -a name.cif. The result is on the display
screen.
−
Terminal window instruction:
platon -O name.cif. The result is in file name.ps.
−
Terminal window instruction:
platon name.cif. Click in main menu 'ORTEP'.
11.4 - How to Look for Missed or Pseudo Symmetry
11.5 - How to Search for Voids in a Structure
11.6 - How to Run SQUEEZE
11.7 - How to Fit two Molecules
11.8 - How to Make and Manipulate Contoured (Difference) Maps
11.9 - How to Transform Reflection Data Including Direction Cosines
Information on the PLATON HKLF4 transformation tool can be found in
Section 1.3.7.6.
11.10 - How to Apply the Same Instruction on the Entries of a Multi-Entry CIF.
Chapter 12 – Frequently Asked Questions
Issues that are not addressed as HOW-DO's in
Chapter 11 are treated in this chapter. Many
answers will point back to sections in this manual to avoid too much repetition.
Why do the values of bond distances and bond angles calculated by PLATON differ
sometimes in the last reported decimal from those reported by SHELXL ?
The difference is the effect of rounding. Distances and angles calculated by SHELXL are
based on the unrounded coordinates available within SHELXL. Distances and angles
calculated by PLATON are based on the rounded coordinates as reported in the SHELXL
created CIF.
Why is there sometimes a difference between the symmetry codes for hydrogen bonds
calculated by SHELXL as opposed to those reported by PLATON ?
PLATON uses a set of standardized symmetry operators that might differ from those
available in SHELXL (either user supplied or created internally by inversion). In particular,
SHELXL does not standardize the translational part of symmetry operations to be in the
range 0 to 1.
Why is there a slight difference between the s.u.'s reported by SHELXL and those reported
by PLATON ?
Standard uncertainties reported by SHELXL are based on the full covariance matrix that is
available from the least squares refinement. PLATON has only access to the parameter
variances reported in the CIF. Differences are generally small.
Why are there label format restrictions ?
PLATON was designed (1980) to work with SHELX76 that had only up to four character
labels. In addition, labels are interpreted to find out the atom type that is used for sorting and
geometry analysis. Also, for geometry tables and molecular graphics, short and clean labels
might be preferable. In order to add some flexibility the concept of label aliases was
implemented. Labels that do not fit in the PLATON regime are given a temporary label that
fits in the regime. Original labels are listed and shown wherever possible.
Why does PLATON transform my I2/a structure to standard C2/c ?
There are many pro's and con's for either the standard setting C2/c or the I2/a setting with a
closer to 90 degrees beta angle. Some are historical such as parameter correlation in non-full
matrix least squares refinement. The default in PLATON (e.g. ADDSYM) is the standard
setting. However, this can be overruled with the KEEP instruction.