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 MENU

The 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 B-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).

Note that the #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 iaut, see below); if you have more coordinates than degrees of freedom, you will have to throw away some of them (commands 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.