[molpro-user] MCSCF Convergence and orbital saving.

[Luke Hartley Thomas]

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