FREQUENTLY ASKED QUESTIONS


PLATON HOMEPAGE

This page addresses questions that were recently communicated.

See also What is PLATON and how to get Started


QUESTIONS

  1. What is the allowed atom naming syntax in PLATON ?

  2. How to calculate the angle between user-defined planes ?


ANSWERS

  1. What is the allowed atom naming syntax in PLATON ?

    Currently only A4 format labels are allowed on input to PLATON.
    The exceptions on this rule are parentheses, underscore and symmetry extensions (see below).

    Atom labels are interpreted (parsed) into three parts, each with their own meaning:

    1. Element type (e.g. Pt, C or H)

    2. Serial number (e.g. 999, 88Y, 17', 0)

    3. Symmetry extension (e.g. a, b, c)

    This information is used for sorting purposes and table lookup of atomic type related properties (radii etc.)

    Parentheses or an underscore are required when the interpretation of the label is not unique.
    e.g. Cu(2A)a, Cu(), Cu1A_a

    Other examples of valid labels:

    Cu99, C999, H12"

    Atom labels that do not fit in the scheme given above are converted automatically into generated labels (e.g. C#1, C#2, N#1 etc).

    Note: Labelling schemes in use in macromolecular crystallography will probably require some editing to fit within the current syntax rules.


  2. How to calculate the angle between user-defined planes ?

    In general, angles between planes (generated by the program) will be calculated and listed automatically as part of a CALC INTRA or CALC instruction.

    When relevant, additional planes can be defined. This should be done before any CALC instruction is given.

    Example: Calculate angle (with s.u.) between (C1 C2 C3 C4) and (C5 C6 C7):

    Enter the following instructions on the prompt ''>>' after the invocation of PLATON with the appropriate data file:

    LSPL C1 C2 C3 C4
    LSPL C5 C6 C7
    CALC GEOM
    END

    The result will be in the .lis and .lps files.

    Note: The number of planes given can be more than one; all n * (n - 1) / 2 inter-plane angles will be calculated.


PLATON HOMEPAGE


24-09-1999 A.L.Spek