[molpro-user] QSD optimization error

[Omololu]

Hi,

Maybe you should start the aug-cc-pVTZ calculation
using the optimized geometry from your cc-pVTZ
calculation as the starting point. My first guess
would be that the starting geometry is somewhat far
from the minimum.

o.

--- Nicholas Marshall <nmarshal at hermes.ccqc.uga.edu>
wrote:

> Dear Molpro users,
> 
> I have a strange problem with a reaction-coordinate
> following
> optimization that I am attempting.
> 
> ***,title
> memory,270,m
> file,2,leu_mp2qsd.wfn,new
> 
> gthresh,energy=1.d-10,optgrad=1.d-6,optstep=1.d-4
> 
> (definitions of z-matrix variables)
> 
>    geometry={angstrom;nosymm;
> 
>     (z-matrix goes here)
> 
>     }
>    basis=STO-3G
>     hf
>     wf,72,1,0
>     frequencies,analytical
>    save,5300.2
>    basis=aug-cc-pVTZ
>     hf
>     wf,72,1,0
> 
> direct
>     mp2
>     core,9
>     optg,maxit=200
>     method,qsdpath
>     numhes,-1
>     hstart,5300.2
>     print,opt
>     put,molden,atz_mp2_opt.mol
> 
> This optimization goes completely wrong, producing a
> nonphysical
> geometry with far-too-short bond lengths. The energy
> actually increases
> during the optimization. The same optimization works
> normally with the
> cc-pVTZ and STO-3G basis sets.
> 
> Note that in the above calculation, I have used a
> starting STO-3G SCF
> Hessian, but the problem still occurs if the default
> Hessian from the
> force field is used.
> 
> Note that this is a large molecule, with 22 total
> atoms.
> 
> Does anyone know what could be happening?
> 
> Thanks very much,
> 
> Nicholas Marshall
> 2nd year graduate student
> Center for Computational Chemistry, University of
> Georgia
> 
> 


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