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.