2026-10-05: preparing the 32-EC pilot#

The ethylene carbonate (EC) reference, as decided on 2026-10-05: QZ pairs and TZ triples, no counterpoise, with criterion “contact”, a pair cutoff of 4.5 Å and connected triples within 3.0 Å. The low level is mixed: VASP for the monomers and close pairs, ORCA for the rest, and the cell at the VASP level.

What it needed#

  • A high level per order: seamm-mbe 2026.10.5 (high_by_order) and mbe_step 2026.10.5 (the “triples high level” and the increments_c<id>.json file).

  • Fragments through different images: seamm-mbe 2026.10.5.1. The 32-EC cell is narrower than the uniqueness bound, which is 20.07 Å for these pairs and 25.61 Å for these triples, so the same molecules can form several triples.

    • Each of these triples is enumerated. The minimum-image one keeps the plain name and the others carry their images.

    • A molecule bonded to two images of a partner only skips the placement that would hold the partner twice.

    • A molecule within the pair cutoff of its own image is refused.

Expected counts for the pilot frame#

The frame is from ChemAI job 5170: 32 EC, a cubic cell of 15.2423 Å, with the cell held fixed in the minimization. Enumerated with seamm-mbe 2026.10.5.1 at the settings above, it gives:

  • 2 warnings, one for the pairs’ bound and one for the triples’;

  • 32 monomers;

  • 241 pairs, 15.1 contacts per molecule;

  • 878 connected triples. Fifteen molecule sets each form three different triples, e.g. (0, 1, 25) gives t00_01_25, t00_01_25_xm0mm0m and t00_01_25_xm00m00;

  • 443 auxiliary pairs, the triples’ outer pairs and image pairs;

  • 1,594 fragments in all, with unique names.

A pilot run on this frame should list exactly these. A different count means the enumeration or the settings changed.

The staged pre-pilot (TinkerCliffs job 7859415)#

The pre-pilot ran before the image fix, so its 48 fragments were sampled from the 2×2×2 supercell, where images are not ambiguous. Each fragment was mapped back to the 32-EC cell’s grid. The run computes:

  • all 48 fragments with VASP in a box the size of the cell;

  • all 48 with ORCA at TZ, and the 43 monomers and pairs at QZ;

  • the tightest stacked pair, d00_26, and its two monomers with VASP in a 1.5× box.

It compares the VASP and ORCA increments by body order and contact class, and the pair’s box-image effect at 1.5×.

The probe calibrated the VASP cost:

  • an EC monomer in the cell-sized box took 1,543 s on 8 ranks, 3.4 core-h, with a peak of about 2.3 GB per rank, so 4 GB per rank is needed;

  • that is 0.656 of the model’s time.