[molpro-user] noncanonical orbitals in CCSD-F12

[Mariusz Radon]

On 01.03.2013 12:59, Gerald Knizia wrote:
> On Thu, 2013-02-28 at 11:23 +0100, Mariusz Radon wrote:
>>
>> Unfortunately, it seems that Molpro always performs at least 3 HF
>> iterations (even if maxit is set to 1 or 0, or -1)....
> 
> I am rather sure that I fixed this a few years ago: {hf; maxit,1} should
> now always perform exactly one iteration, just make a new Fock matrix,
> and not update the orbitals. I am not sure in which released version
> this first occurred, but it might be helpful to update your Molpro
> binaries if you are using old ones. 
> 

Yes, I used the 2010.1 release in these calculations. Kirk Peterson
already told me the same: that this issue has been corrected (probably
in the 2012 release). Thank you for confirming this. Maybe I will give
it a try later with the newest version.


>> Or am I obtaining "good" results by pure accident?
> 
> I would recommend not using the KS-Fock matrix directly. It will
> actually be mixed with other Fock matrices (for the RI-space), and they
> do not have the exchange-correlation contributions. It is quite likely
> that at the very least you would get very wrong CABS singles energies.
> 

Thank you for this warning and for your suggestions. I will keep it
under my consideration.


Kind regards,
Mariusz Radon

-- 
Dr Mariusz Radon, Ph.D.
Coordination Chemistry Group
Faculty of Chemistry
Jagiellonian University
ul. Ingardena 3, 30-060 Krakow, Poland
http://www.chemia.uj.edu.pl/~mradon