[yury-lysogorskiy]

Release 0.1.4: the files of the tag 0.1.4 (one commit). Merge with Rebase and merge.

GRACE-1L/2L models with max_order 3, faster GPU kernels for the GRACE-OFF models, and GRACE-2L results near the
cutoff that match TensorFlow.

Added

• GRACE-1L and GRACE-2L models with max_order 3 (no AAAA / BBBB products; for example the small GRACE-OFF
  models) run on the CPU and on NVIDIA and AMD GPUs, in Python and in LAMMPS, with the same results as TensorFlow.
  Such models have no uncertainty head. GRACE-2L files of such models need export_kokkos of a tensorpotential newer
  than 0.6.2.1; GRACE-1L files exported earlier load as they are. Older grace-runtime versions refuse such files
  (fc_AA2_w_left missing).

Fixed

• GRACE-2L near the cutoff: the RMSNorm epsilon is now 1e-10, the value of tensorpotential (was 1e-8). Energies and
  forces change where atoms have few neighbors or bonds close to the cutoff (molecules, surfaces, dissociation), by up
  to 2 eV for a dimer 0.05 Å inside the cutoff, and now agree with TensorFlow there. Bulk results are not visibly
  affected.
• CPU: after a call that stopped with the error for two atoms at the same position, the next call on the same
  calculator returned wrong forces (the bond forces of the failed call were added; energies were right).

Changed

• Faster GPU kernels, mainly for the GRACE-OFF models:
  • GRACE-1L: GPU kernels of their own for FC widths 20 and 48 and for radial widths up to 32 and 48 (before:
    zero-padded to 32 or 64).
  • Models with lmax 3 get the wave-per-atom bond backward and, on AMD CDNA GPUs, the matrix-core basis kernels
    (before: lmax 4 only).
  • The specialised CG-product kernels are chosen product by product instead of for a whole model shape, so models
    whose products match only partly (the GRACE-OFF models, GRACE-2L-OMAT, GRACE-2L-OAM) use them too.
  • AMD GPUs: the GRACE-2L layer-2 backward of models with 48 layer-2 channels and lmax 4 fits more teams per compute
    unit.

Time per atom and step (µs; Python, fixed positions), about 5,000 atoms of water (GRACE-2L-OMAT: bcc W), before and
after these kernels:

Model	RTX 4070 SUPER	MI250X (one GCD)
GRACE-OFF-1L-small	0.85 → 0.54 (−36 %)	1.35 → 0.70 (−48 %)
GRACE-OFF-1L-large	3.81 → 2.67 (−30 %)	3.08 → 2.13 (−31 %)
GRACE-OFF-2L-small	2.04 → 1.96 (−4 %)	2.84 → 2.28 (−20 %)
GRACE-OFF-2L-medium	3.56 → 3.45 (−3 %)	4.50 → 3.74 (−17 %)
GRACE-OFF-2L-large	4.85 → 4.64 (−4 %)	5.68 → 4.60 (−19 %)
GRACE-2L-OMAT	3.72 → 3.50 (−6 %)	3.94 → 3.07 (−22 %)

Results change at the level of fp32 rounding only.

LAMMPS (grace-runtime branch of the LAMMPS fork)

• Builds grace-runtime 0.1.4: the models, fixes and GPU kernels above.

Documentation

• Models: fits with max_order 3; exporting a model published as saved_model/ only; the GRACE-1L widths with GPU
  kernels of their own.
• Benchmarks: the time-per-atom chart names its benchmark system.

Changed defaults

• NVIDIA GPUs: GRACE-1L models with lmax 3 use the wave-per-atom bond backward (GRACE_FUSED_WAVE_BWD, which still
  switches it either way).
• GPU padding of GRACE-1L fits: FC widths up to 20 pad to 20 (was 32), from 33 to 48 pad to 48 (was 64); radial
  widths up to 32 run unpadded (was: padded to 32 unless they divide 256), from 33 to 48 pad to 48 (was 64). The
  padding warning names the new widths.