ext94b.man

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)