Posted by Jellby on March 12, 2007 at 18:27:44:

Hi all,

While doing some tests I found that the Hessian given by MCKINLEY is different from the Hessian I get, for example, with Gaussian98. I made a calculation for H2 (SCF/STO-3G), and I got the same energy and gradient in both programs, but the Hessian is not the same. Actually, there are two types of non-zero values in the Hessian, one of them is the same, the other is not (and it's a significant difference). Is there any component or computation I'm missing? I'm reading the "Complete static Hessian" section in the output, and I'm doing calculations without symmetry.

I wanted to try a numerical Hessian to compare them, but I'm a bit confused. It looks like SLAPAF should do it, but I cannot get it to work. Can anyone provide a minimal sample file for a numerical Hessian calculation?

For the record, this is my molcas input file:

==================================

&SEWARD &END

Title

H2 molecule

>>> coord inline basis STO-3G

NoSymm

2

H 0.0000000 0.0000000 0.0000000

H 1.0000000 0.0000000 0.0000000

End of input

End of input

&SCF &END

End of input

&ALASKA &END

End of input

&MCKINLEY &END

ShowHessian

NoMCLR

End of input

==================================

And this is the gaussian input:

==================================

#P HF/STO-3G Freq

FCheck=All NoSymm

H2 molecule

0 1

H 0.0000000 0.0000000 0.0000000

H 1.0000000 0.0000000 0.0000000

==================================

Thanks in advance.

- Re: Hessian calculation
**Roland Lindh***10:27:50 3/23/07*(1)- Re: Hessian calculation
**Jellby***12:13:28 3/23/07*(0)

- Re: Hessian calculation
- Re: Hessian calculation
**Jellby***11:09:22 3/21/07*(0) - Re: Hessian calculation
**Jellby***09:56:11 3/13/07*(0)