Large GAs used without preallocation warning

[Jacopo LUPI]

Dear Molpro users and developers,

I am running with molpro 2021.3 some F12 geometry optimizations on small vdW complexes. In the log file, in the middle of MP2-F12 iteration, this warning appears:

? Warning
 ? Large GAs used without preallocation
 ? The problem occurs in mpp
 The results below MAY BE INCORRECT!
 See "Running Molpro on parallel computers" in Molpro manual.

Should I be worried about this?

Here I attach the input file

***,pcb;
memory,1000,m
wf,charge=0,spin=1,elec=27,sym=1

 B1=                  1.34476905 ANG
 B2=                  2.27450744 ANG
 A1=                175.35583635 DEG
 B3=                  0.96128241 ANG
 A2=                118.01765989 DEG
 D=                  54.38103712 DEG

geometry={
 S
 H,1,B1
 O,2,B2,1,A1
 H,3,B3,2,A2,1,D,0
 H,3,B3,2,A2,1,-D,0
}

basis=cc-pwCVTZ
{rhf,so-sci}
{mp2-f12}
{optg,gaussian,srms=4.e-6,grms=1.e-6}

Thank you in advance

Best regards

--

Jacopo Lupi

PhD Student in Methods and Models for Molecular Sciences

SMART Laboratory

Scuola Normale Superiore

Piazza dei Cavalieri 7, 56126 Pisa (Italy) 

[qia...@theochem.uni-stuttgart.de]

Yes, you should be worried and check out "Running Molpro on parallel computers" in Molpro manual.

I take that you are running the calculation on multiple nodes? Some file I/O is then implemented using the GlobalArrays library, and failure in preallocation is know to give wrong results with some computers. You can pre-allocate some GA memory, use a mpi-pr build of Molpro, or run single-node calculations to get things right.