Subject: Angle force constants

From: "Oscar Rey" <[email-masked]>
Date: Fri, 5 Jan 2001 14:14:32 -0000

Dear colleagues:

I'm trying to develop some new AMBER parameters for my molecules. I have
some problems to develop the angle force constants from the hessian
matrix.
I've read the AMBER home page but I only got information about
calculating bond distance force constant. Does anybody know any
reference about it or how to do it?

Thanks in advance!

Oscar Rey Puiggros
Computational Chemistry Group, Molecular Engineering Group (GEM)
Institut Quimic de Sarria (Ramon Llull University)
Barcelona

---

From: "Victor Anisimov" <[email-masked]>
Date: Fri, 5 Jan 2001 16:05:17 +0100

Hi Oscar,

I can recommend you looking into GAMESS US. It has a function of converting
Cartesian Force constant matrix into internal coordinates. This way you will
get force constants of bonds, angles and torsions calculated. As you know
there is no strict way of obtaining force constant related to particular
internal
coordinate for many-atom molecule but at least the method used in GAMESS is
the best a theory can suggest now. If you will find anything better I'd be
very
interested getting your summary.

GAMESS manual has a few references pointing onto original publications
regarding this conversion of Force constant matrix.

If you have Gaussian, GAMESS, or MOPAC2000 Force constants calculated
you may take a look onto ISOEFF98 program that will help you playing with
different Z-matrix and will do for you this conversion of Cartesian force
constants into internal coordinate representation. The program is designed
for isotope effect calculation but you may find it useful for your case too.

A Web site of ISOEFF98 is:
http://ck-sg.p.lodz.pl/isoeff/isoeff.html
The program is distributes as open source, so you can compile it under
any platform. Windows and Linux binaries are available too. Any feedbacks
about the program are welcome.

In case you need any help do not hesitate to contact me.

With regards.
Victor.

==========================================================================
Victor Anisimov, PhD, Senior Software Researcher - Computational Chemist
FQS Poland, ul. Starowislna 13-15, 31-038 Krakow, Poland
Email: [email-masked]  Tel.(+48 12) 429-4345  Fax(+48 12) 429-6124
==========================================================================

----- Original Message -----
From: Oscar Rey <[email-masked]>
To: <[email-masked]>
Sent: Friday, January 05, 2001 3:14 PM
Subject: CCL:Angle force constants

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