Subject: Force Constant in G94?

From: Cheol Choi <[email-masked]>
Date: Tue, 14 Nov 1995 09:25:54 -0500 (EST)

Dear Netters:

Recently, we got the Gaussian 94.

In G92 geometry optimization, it actually calculates the
Hessian matrix and force. 
Since G94 uses the redundant coordinate, there might be a big
change in geometry optimization.
But what I still need is the Hessian matrix in Cartesian Coordinate.
Since frequency calculation is expensive, I don't like to try it.

So I used the opt=z-matrix option to get hessian matrix in cartesian 
coordinate.
That option gave me the hessian matrix with sto-3g basis set but not with
larger basis sets.

I don't know why larger than sto-3g basis set didn't give me the hessian
metrix. (In fact, the hessian only can be extracted from checkpoint file.)

Please, let me know how to get hessian metrix with larger basis sets.

Thanks a lot.

Cheolho Choi
Georgetown Univ.