[molpro-user] Counterpoise correction for ion-molecular complexes

[Yang, Shengfu F. (Dr.)]

Dear All,

Grant is probably right. The error information comes out as following:

The number of valence orbitals is .le. 0.
 One possible cause of this is that there are no orbitals available, ie you might have forgotten
 to do a Hartree-Fock calculation. Another possiblity is that the number of electrons is .le. half
 the number of uncorrelated core orbitals.

I have mistyped in the example, where a Na should be used instead of Li (dummy, Li; ==> dummy, Na).

What do I need to do in order to correlate all electrons? Grant indicated that the basis set for Na should be changed. Do I need to do anything more than that?

Thanks,

Shengfu

-----Original Message-----
From: Grant Hill [mailto:jghill at wsu.edu] 
Sent: 01 February 2010 15:30
To: Yang, Shengfu F. (Dr.)
Cc: molpro
Subject: Re: [molpro-user] Counterpoise correction for ion-molecular complexes

By default MOLPRO employs the frozen core approximation. This means that Li+ has no electrons to correlate in the CCSD(T) calculation. 

You could try to remedy this by correlating all electrons, but you will probably need to change your basis set.

HTH,

Grant


On 1 Feb 2010, at 04:20, Yang, Shengfu F. (Dr.) wrote:

> Dear All,
> 
> I have got a problem with the counterpoise correction for ion-molecular complex. For example, part of the input file is: (Na+He)
> 
> {rhf; wf, 12,1, 0);
> rccsd(t);
> E1 = energy;
> 
> dummy, He;
> {rhf;wf,10,1,0}
> rccsd(t);
> E2 = energy;
> 
> dummy, Li
> hf;
> ccsd(t);
> E3 = energy;
> 
> dummy;
> ....
> 
> The error is always something like "there is no obital ...." for the counterpoise correction of Li+. Can I ask what the solution is for this problem?
> 
> Thanks a lot for your help!
> 
> Sincerely Yours,
> 
> Dr. Shengfu YANG
> -------------------------
> Department of Chemistry
> University of Leicester
> Leicester LE1 7RH
> UK
> Tel: +44-116 252 2127
> Fax: +44-116 252 3789
> -------------------------
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