[molpro-user] MCSCF Convergence and orbital saving.

[Alexander Mitrushchenkov]

Luke,

The answer to your first question could be the change in the closed shell
occupation, which you can check in the output. In principle, it should be 
restarted correctly, and I will verify and make a bug report if this is not 
the case. In the meantime, to avoid problems, you could specify explicitly 
the number of closed-shell orbitals.

For the second question, I guess most of the input for MULTI is ignored when 
doing a geometry optimization. Specifying the global thresholds should work 
though, like

gthresh,energy=0.2e-6

somewhere before and outside of the MULTI input. This is described in section 
10.11 of the manual. Please note that you may need to change the threshold 
for STEP too.

Please let us know if this helps.

Cheers,

Sasha


On Wednesday 20 June 2007 13:43, you wrote:
> Dear Molpro users,
>
> I am trying to undertake some MCSCF and MRCI calculations with MOLPRO
> 2006.1 patch version 40, but I am having a few problems that I cannot solve
> with the help of the manual.
>
> Firstly,
>
> When I perform an MCSCF calculation with the following input, the
> calculation proceeds normally.
>
>  memory,100,m
>  file,2,bcl3-min1-mcscf-big.wfu
>  gprint,orbital=5,basis
>  r1=1.758 angstroms
>  r2=1.7581 angstroms
>  r3=1.758 angstroms
>  a1=120.01 degrees
>  a2=120.00 degrees
>  d1=180.0 degrees
>  geometry={
>  B1,
>  Cl1, B1, r1
>  Cl2, B1, r2, cl1, a1
>  Cl3, B1, r3, cl1, a2, cl2, d1
>  }
>  basis={default,sto-3g}
>  {hf
>  wf,54,1,0}
>  basis={default,cc-pvtz}
>  {hf
>  wf,54,1,0}
>  {multi
>  frozen,0,0
>  closed,13,3
>  occ,25,7}
>  optg
>
> However, when I try to restart the calculation, and save the orbitals, by
> using the input
>
>  memory,100,m
>  file,2,bcl3-min1-mcscf-big.wfu
>  gprint,orbital=5,basis
>
>  geometry={
>  B1,
>  Cl1, B1, r1
>  Cl2, B1, r2, cl1, a1
>  Cl3, B1, r3, cl1, a2, cl2, d1
>  }
>
>  basis={default,cc-pvtz}
>  {multi
>  save,,5000.3
>  frozen,0,0
>  closed,13,3
>  occ,25,7}
>
> the output generates a few new lines of code,
>
>  Maximum number of shells:             8
>  Maximum number of spin couplings:   429
>
> And then the following error message:
>
>        Storage for configuration lists 5182008, coupling
> coefficients3670869, address lists*******
>
>        Molecular orbitals read from record     2140.2  Type=MCSCF/MULTI
> (state 1.1)
>
>        Wavefunction dump at record             2140.2
>
>        Convergence thresholds  0.10E-01 (gradient)  0.11E-05 (energy) 
> 0.10E-02 (step length)
>        insufficient memory available - require              162579456  have
>               15685319
>        the request was for real words
>
>        GA ERROR fehler on processor   0
>
> It appears to be that MOLPRO is trying to do some type of spin orbit
> calculation(?), which seems to be a lot slower, and requires a lot more
> memory than I have available. Can anybody indicate why just saving the
> orbitals should cause molpro to behave in this way, and can I do anything
> to prevent it? I wish to use the orbitals as the reference for a CI
> calculation.
> I notice that MOLPRO 2002.3 did not behave in this way - the save command
> just caused the same calculation as before to be performed.
>
> Secondly,
>
> I would like to change the convergence criterion on the MCSCF energy
> calculation during my geometry optimisation. Again, I have consulted the
> manual, but I do not seem to have any success with the commands given.
>
> My input is as follows:
>
>  memory,100,m
>  file,2,bcl3-ts5-mcscf-big.wfu
>  gprint,orbital=5,basis
>
>
>  geometry={
>  B1,
>  Cl1, B1, r1
>  Cl2, B1, r2, cl1, a1
>  Cl3, B1, r3, cl1, a2, cl2, 180.0
>  }
>
>  basis={default,cc-pvtz}
>  {multi,
>  frozen,0,0
>  closed,13,3
>  occ,25,7
>  thresh,energy=0.2e-6}
>  put,molden,bcl3-ts5-mcscf-big-sp.mld
>  {optg
>  root,2
>  method,qsd
>  hessian,read}
>
> The manual also suggests I can use the command "energy" after the multi
> command to change the convergence threshold. I have tried:
>
> multi,energy=0.2e-6
>
> and
>
> multi
> energy=0.2e-6
>
> neither of these seem to work. Either the calculation complains about the
> syntax, or just carries on with the normal criterion, 0.1e-7.
>
> I have also tried:
>
> accuracy,energy=0.2e-6
>
> in the MULTI command block.
>
> This is also ignored. Is this problem something to do with the optg command
> altering the convergence thresholds after I have changed them? I believe
> that the convergence criterion is tighter when performing an optimisation
> of the geometry. Can anybody suggest the correct syntax to use.
>
> Many thanks in advance for your help, (and sorry for the length of the
> enquiry!)
>
> Luke Thomas
> Department of Chemistry
> University College London

-- 
Dr. Alexander Mitrushchenkov

Universität Stuttgart
Institut für Theoretische Chemie
Pfaffenwaldring 55
D-70569 Stuttgart

Tel +49 (0)711 / 685-64409
Fax +49 (0)711 / 685-64442
Mail sasha at theochem.uni-stuttgart.de