Subject: Request: Prog or code to convert xyz f. const to int.

From: [email-masked] (Edward Wolpert)
Date: Mon, 24 Jan 94 12:52:05 EST

Netters-
	I'm trying to write a little program to convert force constants from
xyz co-ordinates to internal co-ordinates without having to worry about
redundencies.  This code would assume the force constants in xyz and b-matrix
already exist.  (They come from hondo 8.2)  I'm also interested in programs
that are freely available that do this already.  Due to my limited funding,
I'm not currently able to get the proper programs from QCPE that do this.
I do not need to generate the vibrational frequencies, just convert force
constants from one format to another.  

	I know that the following should work:
		F(int) = B x F(xyz) x B-1
where B is the b-matrix, and B-1 is the transposed b-matrix.  However, I
noticed that in hondo, they seem to use the inverse B matrix instead.  I
would like to use the 'normal' b-matrix for such work.  Also, to be able to
convert the units within the program.  If such a program exists in the public
domain, please send me information on it.  If not, I would like suggestions
on how I can write such a program.  Once written, I will be more than happy to
put the source code in the public domain, giving credit to those who help.
My current work is in C, but current fortran code is also useful.
		Virtually,
		Edward Wolpert

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