Bug in running B3LYP with IVDW=12

[KWH]

I encountered a bug in attempting to do a b3lyp with GD3 vdW correction. Attached are all the associated files. How do I fix/get-around this?

[michael_wolloch]

Dear KWH,

I tried to reproduce the bug on a small workstation using an Intel OpenMP compile of version 6.2.0 (as you seem to have) on 8 ranks and 2 threads. The calculation finishes the first SCF cycle normally, but segfaults at the first ionic update (also not good, but different).

However, when I use only one OpenMP thread per rank, the error you observe appears.

Please try again with 4-8 MPI ranks and a couple of OpenMP threads for each rank, and report back. The very large number of MPI ranks you used (124) for such a small system will not speed up the calculation.

As a side note: your setting of NCORE=124 is extremely inefficient. Usually, for an OpenMP compile, it is ignored anyhow and reset to 1 internally, but only if OMP_NUM_THREADS>1. If you are using an OpenMP build, make sure to set OMP_NUM_THREADS to a reasonable value for your system (e.g., 4 to 8 is usually fine), or set NCORE as described in the documentation, to get performant FFTs.

Otherwise, you can try to compile without OpenMP.

I tested a bit with the current release version, 6.6.0, and did not encounter the bug you found, even when running with only 1 thread with the OpenMP version. However, I did sporadically encounter another bug that I will investigate.

Let me know if setting OMP_NUM_THREADS>1 works for you,
Cheers, Michael