AIMPAC Utilities						    extreme(3)

NAME

     ext94b - interactively determines the locations of extrema (that 	  
	  is, critical points) in the electron density, RHO (1), Laplacian
	  of RHO, DEL**2(RHO) (2), Lagrangian Kinetic Energy Density, G 	  	  
	  (3), Hamiltonian Kinetic Energy Density, K (4), Nuclear 	  
	  Potential, Vnuc (5), and Potential Energy Density, V, the virial 	  
	  field (6).

SYNOPSIS

     ext94b wfnfile 

DESCRIPTION

        ext94b reads in the geometry and wavefunction from the wfnfile 
        and then interactively queries the user for information.  The 
        user may ask to find the locations of critical points in rho, 
        del-square-rho, G, K, Vnuc or V by starting from a given point 
        or the midpoint between atoms.  ext94b may also be used to 
        determine the properties of the electron density at a particular 
        point, as well as to determine the bond path length and bond 
        path angles.

ARGUMENTS

     wfnfile (for example 'c4h4.wfn')
        The wavefunction file contains the primitive basis set and 
        optimized primitive coefficients for the occupied orbitals of 
        the molecular wavefunction.

INTERACTIVE DIALOG

	The user will be prompted with the title of the wavefunction
	file and then asked to supply a title for that particular
	run of ext94b.  The user will then see the prompt,

	COORDS or NUCLEAR (0), BOND (1), RING(2), CAGE(3), ANGLE (4),
	POINT (5), MEGA(6), OPTION(7), LIST CURRENT CP'S(8), STOP (9)

	Choosing (1) locates a bond or (3, -1) critical point. The user
	is prompted to choose a pair of atoms between which the critical
	point is to be searched for and then is asked at which point the
	search is to begin. This point is used as the starting point of
	the quasi-Newton-Raphson search for the nearest extremum with the
	designated curvatures.  If a critical point is found for RHO,
	the user is asked if the trace of the bond path is desired.  This
	MUST be done if the bond path angles are desired.

	Choosing (2), the program searches for a ring critical point or
	(3, +1) and the user is prompted to name three atoms in the
	perimeter of the ring.

	Choosing (3), the program searches for a cage or (3, +3) critical
	point and the user is asked to name four atoms in the surfaces
	bounding the cage. In some cases, the initial point in the search 
	for a ring or cage critical point chosen by the program is too far
	removed from the correct position and the user must then use his
	intuition to make a better guess (0).
                 
	If (4) is chosen, the user is asked to name three atoms, 1, 2, and
	3 that are linked by bond paths. The geometric and bond path 	
	angles are then given.  The bond path must have already been 	
	traced for each of the atomic pairs involved. The bond path angle 	
	for atoms 1-2-3 is the limiting angle formed by the two bond paths 	
	that terminate at the central nucleus 2. It may be greater than 	
	(bond paths outwardly curved) or less than (bond paths inwardly 	
	curved)the geometrical angle.

	If (5) is chosen, the user is prompted for a set of Cartesian
	coordinates. The properties of the scalar function at that point
	are given.

	If (6) is chosen, all critical points of a given type are searched
	for. One may also request that the search be done for all types 
	of critical points.

        Choosing (7) enables one to change the parameters in the 
        program, such as accuracy to used in evaluating the function, 
        the print options, or the gradient threshold for labelling a 
        point a critical point etc.

	Choosing (8) causes the current critical points to be listed.

OUTPUT

	ext94b generates a file containing the information determined
	in the run.  This file will have the file extension '.crt'.  

        NOTE ALL VALUES ARE GIVEN IN ATOMIC UNITS!!!

EXAMPLES

     ext94b c4h4

        This requests an interactive determination of the extrema in
	rho, del-square-rho, G, K, Vnuc or V using the wavefuction in 
	c4h4.wfn.

SEE ALSO

     proaimv(3), grdvec(3), bubble(1)

Release	2.0			  AIMPAC			    extreme(3)