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Cameron Manual

Chapter 19: Distance And Angle Calculations

19.1: Method of Calculation

CAMERON allows the user to calculate distances , angles and torsion angles.

DISTANCE

In order to perform a distance calculation two atoms lists must be generated. The first list is used as a 'starting atom' and the second list is for 'target atoms'. Distances will be calculated between atoms in separate lists BUT NOT within the lists themselves. The list may be generated in two ways:-

 DISTANCE N O
 


generates two lists - both of which can all the N and all the O atoms. In this case N-O, N-N and O-O distances will be found.

FROM
TO These subcommands allow to specify different starting and target atoms.
 DISTANCE FROM N TO O
 


will only calculated N-O distances. Note that the distance arguments may be either atoms or elements as required.

RANGE This sets the minimum and maximum ranges for displayed distances. The syntax is :-
 DISTANCE RANGE dmin dmax
 


distances are given in angstroms. If only TWO atoms are present in the atom list then the distance will be outputted irrespective of the range. However, as the full calculation will be carried out first there may be a time delay while the calculation proceeds.


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19.1: Method of Calculation

The distances output make use of the symmetry operators in order to find distances within the given range. The starting atom coordinates are NOT ALTERED but those of the target atoms are. The symmetry operators (and any suitable translations) are used to move the target atoms around. The output produced is:-

 N1_0      O2      2.323
 Operator x y z Translations 0 0 1
 N1_0      O2_4    1.114
 Operator -x y+1/2 -z Translations 0 0 -1
 


These show the N1 to O2 distances. The first distance relates to an O2 atom which does not currently exist. The operator and translations shown can be used with ADD to generate the atom if required. The second distance is to an atom (O2_4) which does exist. ie. if no pack number is given for the second atom it is not present in the current list.

ANGLE
TORSION

These commands are used to find angles and torsion angles between atoms that are in the current list. They are entered in sets of three (or four) as required.



[Introduction | How To Get Started | Data Input | Outputting Data | Editing The Atom List | Obeying Files | Archiving And Retrieving Views | Graphical Output Devices | View Direction Control | Include And Exclude | Drawing Style Control | Connectivity Control | Control Of Colour | Atom Labelling | Other Picture Controlling Commands | Symmetry Input | Crystal Packing Commands | Add And Move - Further Symmetry Related Commands | Distance And Angle Calculations | Information On Data Held Within The Program | Group Definitions | Miscellaneous Commands | How To Stop The Program | Menu Definition File | Some Useful Ideas ]

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© Copyright Chemical Crystallography Laboratory, Oxford, 2006. Comments or queries to David Watkin - david.watkin@chem.ox.ac.uk Telephone +44 1865 285019. This page last changed on Wednesday 8 November 2006. The website was re-generated on Wednesday 8 November 2006. Choose your nearest mirror for faster access: [ Original | CCP14 UK Mirror | CCP14 Canadian Mirror | CCP14 USA Mirror | CCP14 Australian Mirror ]
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