SINGULARITY IN SCHMIDT ORTHOGONALISER ISTATE = 1

[Reetu]

Hi everyone,

I am new to Molpro and want to run some optimisation calculations on MOLPRO. But, I am keep getting this error. 

****  SINGULARITY IN SCHMIDT ORTHOGONALISER
 ISTATE =                      1

Any help would be highly appreciated.

Many thanks

Reetu

[tibo...@gmail.com]

Dear Reetu,

Without more information, the first thing I can suggest is to verify that your geometries and calculation parameters (charge, multiplicity, etc.) are sensible.

If you could post the output file, members of the forum would have more information to work with.

But for a quick shot in the dark, you could try running the calculation with like this MKL_CBWR=COMPATIBLE molpro instead of just molpro

If your installation of Molpro has been built with the MKL linear algebra library, this will force it to take a different, slower code path that may be slightly more numerically accurate, at the cost of speed. This can sometimes nudge problematic calculations out of hitting a singularity.

Alternatively you could also try tightening various integration thresholds to nudge the calculation, like this:

gthresh,twoint=1.d-14
gthresh,compress=1.d-14
gthresh,zero=1.d-14

Of course this also has a speed and memory/disk usage penalty.

Best,

Tibor

[Reetu]

Hi Tibor,

Thanks for your reply. I just run multi calculation. The molecule is neutral. I have attached the input and output file. 

I am using molro on shared cluster. Can you guide me how to run the calculation with MKL_CBWR=COMPATIBLE molpro.

Many thanks

Reetu

[tibo...@gmail.com]

That MCSCF calculation looks...large. You might want to think about using a smaller active space even if the singularity issue is resolved.

MKL_CBWR is just an environmental variable that MKL checks when execution starts. You need to set that environmental variable on the compute node, before Molpro is launched. You can set it the same way you would set any other environmental variable on a compute node. If the cluster admins have some kind of documentation on how to do it, I recommend reading that. I cannot guide you with exact instructions, especially as "shared cluster" can mean multiple things.

If you are using a cluster managed by SLURM and using sbatch to start jobs, then pasting export MKL_CBWR=COMPATIBLE  into the body of the batch file (before Molpro is launched) should be sufficient.

Best,

Tibor