Subject: Determinant of Hessian matrix

From: [email-masked] (Taesung Moon)
Date: Wed, 13 Nov 1996 14:43:47 -0800

Dear netters,

I have tried to evaluate the determinant of Hessian matrix evaluated 
using Discover3.0. The Hessian is positive definite at minimun 
conformation but some determinants are negative in my cases. 
I carried out full minimization using Quasi-Newton 
or Newton-Raphson method until maximum derivative is less than 0.00001.

For example,
---------------------------------------------------------
                      the determinant of Hessian matrix
                      ----------------------------------
 method               butane           alanine dipeptide
---------------------------------------------------------
Quasi-Newton          negative            positive
Newton-Raphson        positive            negative
---------------------------------------------------------

Please let me know the reason. 

Thanks.

-------------------------
[email-masked].