[molpro-user] Derivative coupling

[Alexander Mitrushchenkov]

Hi,

Maybe the error message is misleading; but it wants to say that the 
derivative coupling is zero by definition between states of different 
symmetry, that's why the program refuses to calculate it. It can be 
easily understood if you remember that coupling is nothing more than the 
derivative of overlaps at close geometries, which is zero if symmetry is 
different. If your molecule is not diatomic, and you need couplings for 
deformations that lower the symmetry (and thus become allowed), you 
should lower the whole symmetry from the beggining, as Alan also 
suggested; you do not need in principle to switch it completely off, 
just remove the symmetry that the required deformation breaks.

Hope this helps,

Alexander

Le 25/06/2014 12:06, Rameswar Bhattacharjee a écrit :
> Hi,
> I am trying to calculate the derivative coupling between two states 
> namely 1.1 and 2.6. The programs terminates with a message 
> "Non-adiabatic coupling only for same state symmetry". Is there a way, 
> I can calculate the derivative coupling between states of different 
> symmetry in MOLPnon-adiabatic coupling can be calculated between 
> states of the same symmetryRO.
>
> Also, the derivative coupling program does not allow defining 
> frozen/core orbitals (comment: kraft: no frozen core possible with 
> SA_MC) which leads to a very large occupied space for heavy molecules 
> like Ge3H3 requiring large memory. Is there a way, we can choose the 
> important (active) orbitals and then do a derivative coupling between 
> states of different symmetry?
>
> Thanking You
>
>
>
> -- 
> ---------------------------------------------------------------------------------------------*
> "The man who makes no mistakes does not usually make anything."*
> *Edward John Phelps (1822-1900)*
> ---------------------------------------------------------------------------------------------
>
> Rameswar Bhattacharjee
> Junior Research Fellow
> Dept. of Spectroscopy
> Indian Association for the Cultivation of Science
> Jadavpur, Kolkata-32
>
>
>
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-- 
Dr. Alexander Mitrushchenkov, IGR
Laboratoire de Modélisation et Simulation Multi Echelle
UMR 8208 CNRS
Université Paris-Est Marne-la-Vallée
5 Bd Descartes
77454 Marne la Vallée, Cedex 2, France

Phone:    +33(0)160957316
Fax:      +33(0)160957320
e-mail:   Alexander.Mitrushchenkov at u-pem.fr

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