[molpro-user] Derivative coupling

Alan Chien alandc at umich.edu
Wed Jun 25 15:10:36 BST 2014

Maybe you could try turning symmetry off. Then your states will all have
the same symmetry and will be ordered according to energy. Then you could
ask to compute the coupling between 1.1 and whatever 2.6 ends up becoming
(which you should be able to readily identify since its energy should stay
the same whether symm is on or off).

The only issue is that with symmetry turned off the calculation will take
longer. I don't have enough experience to estimate how much longer, but at
least you should be able to get the coupling that you want.

As for your second question - I'm assuming you are doing an MCSCF/MULTI
calc. If so, it sounds like you are not utilizing the distinction between
closed and frozen. Frozen means always doubly occupied + no orbital
optimization. Closed means always doubly occupied + orbital optimization.
I've calculated derivative couplings with a combination of the *occ* and
*closed* cards to limit the size of the active space. For more details see
the 2012.1 manual - sections 19.2.2 and 19.2.3. It's pretty clear in there.

Hopefully my suggestions work.

~Alan Chien

On Wed, Jun 25, 2014 at 6:06 AM, Rameswar Bhattacharjee <
rameswarb22 at gmail.com> wrote:

> 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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