dsyev problem

[Peterson, Kirk]

Hi all,

 

for a particular linear triatomic molecule, we continue to get the following failure in the frequency calculation:

 

Projecting out rotations and translations

info=                    8

? Error

? failure in dsyev

? The problem occurs in diag2

 

We've tried setting gparam,dsyevd=0 in the input (which seems to get set correctly) but it still fails.  Seems like this is something I've run across before, but I can't remember the fix.  Ideas?

 

best wishes,

 

-Kirk

[tibo...@gmail.com]

Dear Kirk,

You can try forcing the MKL library to take a slower code path using environmental variables, this can sometimes dislodge numerical issues.

Simply launch Molpro as MKL_CBWR=COMPATIBLE molpro instead of just molpro. You can also try if MKL_CBWR=AVX does the tick, if yes, it should be less slow.

Best,

Tibor

[Malathe Khalil]

Dear Tibor 

I put the following in my submission script :

(module purge
export MKL_CBWR=COMPATIBLE
module load molpro/2022.1.2 intel/2021.3-gcc-9.3  impi/2021.3 global-arrays/5.8)

Is it correct to write it this way? or I should include it in the input file? If yes what is the correct syntax?

I appreciate your help. 

Thanks

Malathe

[tibo...@gmail.com]

Dear Malathe,

The MKL env. var. can be set like any other env. var.

If your HPC cluster or queuing system has a recommended way of setting envvars, then follow that.

If not, then the export looks reasonable at first glance.

You can verify that Molpro is indeed seeing the envvar by trying MKL_VERBOSE=1 instead. If this envvar is visible for Molpro, then you should see a lot of text printed by MKL in your job output file (or wherever stdout/stderr gets redirected on your cluster). If MKL_VERBOSE=1 has this effect, you can trust that you have found a way to set envvars that works on your cluster.

Best,

Tibor

[Malathe Khalil]

Dear Tibor

Thank you for the explanation.

I would like to ask also, what is the right way to write “DSYEVD=0” in the input file?

I have tried this method:

{hf;dsyevd=0;

wf,14,1,0;

orbprint,1500}

but I got the following error:

 Input error: Attempt to set Variable DSYEVD in command block

 ? Error

 ? Input error

 ? The problem occurs in check_input

 

Also, I tried to do this way:

{hf;

wf,14,1,0;

orbprint,1500;

gparam,dsyevd=0;}

 

but I got this error:

Checking input...

 

 Unknown directive GPARAM for command HF-SCF

Could you please advise?

Thanks 
Malathe