Internal Coordinate Menu

INTERNAL COORDINATE MENU ( #ideg=6 #k=2 #f=0 #d=0 #i=0 ) imet <a> : PROVIDE B-MATRIX FOR ACTIVE INTERNAL COORDINATES (CHECK COMPLETENESS AND NUMERICAL QUALITY AND CHANGE REDUNDANT INTERNALS TO display) idef : SUB-MENU FOR INTERACTIVE DEFINITION OF INTERNAL COORDINATES ideg <a> : OUTPUT NUMBER OF TOT. SYMMETRIC INTERNAL DEGREES OF FREEDOM iaut : TRY AUTOMATIC DEFINITION OF INTERNAL COORDINATES iman <a> : MANIPULATE GEOMETRY BY CHANGING INTERNAL COORDINATE VALUES imanat <i>: AS iman BUT STARTING AT INTERNAL COORD. NUMBER i ic <i> <x>: CHANGE STATUS OF INTERNAL COORDINATE <i> TO <x> e.g. ic 5 d TO MAKE 5TH COORD. display OR ic k d irem <i> : REMOVE INTERNAL COORDINATE <i>, e.g. irem d TO REMOVE ALL display COORDS dis : ANY DISPLAY COMMAND e.g. disi OR disc disiat <i>: AS disi BUT STARTING AT INTERNAL COORD. NUMBER i WHERE <a>= OPTIONAL ATOMIC SET (DEFAULT=all) <i>= INDEX(LIST) OF INTERNAL COORDINATE(S) LIKE 3-6,8 OR <i>=<x> <x>= STATUS OF INTERNAL COORDINATE = k, f, d OR i ADDING A QUESTION MARK TO ANY COMMAND MAY PROVIDE EXPLANATIONS ENTER COMMAND OR HIT >return< TO GET BACK TO GEOMETRY MAIN MENUThe parameters in the headline of this menu have the following meanings:

`#ideg`- is the total number of symmetry restricted degrees of freedom.
`#k`- is the number of
*active*internal coordinates specified up to now. Only these coordinates are optimized during a geometry optimization. `#f`- is the number of
*fixed*internal coordinates specified. These coordinates will be included in the -matrix (see command`imet`), but their values will not be changed during geometry optimization. `#d`- is the number of internal coordinates whose
values will only be displayed (e.g. by command
`disi`

), but no gradients will be calculated for these coordinates nor will they be included in the geometry optimization. `#i`- means the number of coordinates which are
defined, but will be completely ignored, i.e. they are not even
displayed on the screen and will not be used by any program (this is
the waste-paper-basket of
`define`).

`#k`

plus `#f`

must equal the number of
degrees of freedom (`#ideg`

) of your molecule, if you want to
perform a geometry optimization. If you have less coordinates than
degrees of freedom, you will have to specify further ones (commands
`idef`

or `irem`

or `imet`

, see below).
The commands in this menu allow you to define internal coordinates for your molecule, adjust your geometry to special values of these internal coordinates and to control the numeric reliability of the chosen set of internal coordinates. In detail, the commands act as follows.

- Description of commands
- Interactive Definition of Internal Coordinates
- Specification of available internal coordinates