[molpro-user] Convergence Issues With DIP/QUAD

Tatiana Korona tania at tiger.chem.uw.edu.pl
Mon Jun 20 16:31:42 BST 2011

Dear Gerald,

This script will not work, probably because Molpro detects that no HF 
calculation has been made after a field change. So, in order to make 
orbital-relaxed calculations one should just move HF after DIP, as you 
suggested. If for some reason orbital-unrelaxed properties are needed (in the 
MP2 level they will be quite bad, but for CCSD may be OK), one should use sth 

! no field

maxit,0} ! use no-field orbitals

It is also important to note that DIP+ adds to the existing field, see 
http://www.molpro.net/info/current/doc/manual/node458.html#31876, so better to 
use just DIP, otherwise strange results will appear after several uses of DIP+.

Best wishes,


  On Mon, 20 Jun 2011, Gerald Knizia wrote:

> Michael Morris wrote:
>> I'm having some convergence issues when trying to apply a DIP or QUAD
>> perturbation to my structures. The error arises when MOLPRO gets to
>> performing MP2/CCSD etc calculations: [..]
>> //
>> /HF/
>> /i=1/
>> /DIP+,0.0,0.0,0.001/
>> /{MP2/
>> /CORE,0}/
> While I think that the code here is supposed to work (but would
> calculate orbial unrelaxed properties, which here would likely be very
> wrong), I guess that it can be solved by moving the dip+ before the
> Hartree-Fock. Otherwise the perturbation is not included in the
> mean-field orbitals and mysterious things might happen in the
> correlation treatment following it.
> -- 
> Gerald Knizia
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Dr. Tatiana Korona http://tiger.chem.uw.edu.pl/staff/tania/index.html
Quantum Chemistry Laboratory
University of Warsaw
Pasteura 1, PL-02-093 Warsaw, POLAND

`The man who makes no mistakes does not usually make anything.'
                                        Edward John Phelps (1822-1900)

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