AMBER Archive (2009)

Subject: Re: [AMBER] second derivative matrix

From: Adrian Roitberg (roitberg_at_qtp.ufl.edu)
Date: Mon Feb 09 2009 - 08:29:51 CST

I am not sure what you mean !

A matrix of second derivatives is of course the FIRST derivative of the
first derivative, right ?
Since the first derivatives as computed to get forces, you are in effect
taking the second derivative (cartesian coordinates) of (minus) the forces.

Now, the derivatives themselves are computed analytically. Given the
functional form of the force field, you can write the second derivatives
in a piece of paper, which means you can program them.

Adrian.

Marie Brut wrote:
> Dear AMBER users,
>
> I asked the same question last week, but I received no answer. If
> somebody had any information, it would really help me:
>
> Does somebody know the method used to calculate the second derivative
> matrix in nmode?
>
> Thank you for your help,
>
> Marie
>
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-- 
                            Dr. Adrian E. Roitberg
                              Associate Professor
                             Quantum Theory Project
                            Department of Chemistry

                  Senior Editor. Journal of Physical Chemistry
                           American Chemical Society

University of Florida                         PHONE 352 392-6972
P.O. Box 118435                               FAX   352 392-8722
Gainesville, FL 32611-8435                    Email adrian_at_qtp.ufl.edu

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