Subject: CCL:Summary of internal coordinates --> normal coordinates

From: <[email-masked]>
Date: Thu, 06 Apr 1995 21:58:44 -0300

Dear Netters,

Many thanks to people who replied to my query about converting 
internal coordinates to the normal coordinates.  Here is a summary 
of replies I have received.

Jian Wang
Department of Chemistry
Dalhousie University
Halifax, Nova Scotia
Canada B3H 4J3
Tel: (902)-494-7921
Fax: (902)-494-1310

---------- Original Question ----------

Dear Netters,

I am looking for a code to calculate the matrix which converts the
internal coordinates to the normal mode coordinates.  I can get the
force constant matrix with respect to the internal coordinates, but
I need a code to calculate the G matrix, which is necessary for the
diagonization of the FG matrix.  From there I will be able to
obtain the transformation matrix.

Thanks in advance.

Jian Wang

------------ Replies -------

From:   IN%"[email-masked]"  "Craig Shelley"
==============================

I will be gone the week of March 20th.  I will be back on the 27th.  If you need
support or other information before then, e-mail [email-masked], call
our office at 303-242-7502, or fax at 303-242-6469.

Thanks,

Craig A Shelley

From:   IN%"[email-masked]"
==============================

If you already have code that calculates normal modes in cartesian
X = Lx Q

and to determine the "B matrix"

R = B X ...

(a program that does the former does the latter if the force constants are expresse
d in internal
space)

then the Lr matrix you are looking for is

Lr = B * Lx

where R = int coords
      X  cartesian coords
      Q  normal coords

this is much simpler. programs at QCPE exist for these things.
see the book of Wilson on that topic

**************************************************************************
Dr. Philippe Youkharibache                      e-mail: [email-masked]
Biosym Technologies Inc.
9685 Scranton Road                              tel: (619) 546 5562
San Diego, CA 92121                             fax: (619) 458 0136
**************************************************************************

From:   IN%"[email-masked]"  "Magan Govender - PG"
==============================

Dear Sir,

I have some codes available, and shall be
happy to forward them to you, on request.

Greatings from South Africa

M.G. Govender
Centre for Theoretical and Computational Chemistry
Dept of Chemistry
University of Natal
King George V Avenue
Durban
South Africa

M.G. Govender's second reply:
==============================

Dear Sir,

The program we are using does a complete vibrational
calc. of the secular equation, it is called Vibra by Dr. STeele.
We also have ASYM20, by Ian Mills , obtained from QCPE. A also have a
code from SPectro, author Handy, and Willets, I can send you this
code, and lastly there is a program obtainable via ftp
iqm.unicamp.br, in the chem or pub dir, which is called BGF and NCA,
similar to ASyM20. Anyway I shall forward you the code soon which is
in fortran. The address of Dr STeele is [email-masked].

regards
Magan

From:   IN%"[email-masked]"
==============================

Dear Jian Wang
If you have the B matrix which transform the cartesian force constant matrix
to the internal force constant matrix you can build the G matrix by
G=B M**-1 B#.
Where B# is the transpose of the B matrix and M**-1 is the inverse of
the M matrix. M is a diagonal matrix of tripels of the mass.
The product FG is a nonsymmetric matrix. The simplest way to get
 the eigenvalue and eigenvectors is to bring the matrix to
 a hessenberg matrix then you can get the eigenvalue and eigenvectors by the
 qr methode.
 I wrote  a FORTRAN program which can build the internal force constants matrix
 from the cartesian force constant matrix. Futhermore it will calculate the G
 matrix and frequences. There is also a procedure which bild the B matrix.
 If you are interested in my program please send me a e-mail.
 If you are loocking for some literature for this topic:

Califano Vibrational States
JOHN WILLEY & SONS 1976
T.Miyazawa J. Chem. Phys. 1958 29 P.246
R.J.Malriot J. Chem. Phys. 1955 23 P.30

Futhermore I am intrested in your way to get the internal force constant matrix.
Thanks in advance.
Thomas Nowak
e-mail [email-masked]

--------------  End of Replies ---------