NVIDIA ALCHEMI Toolkit

High-performance deep-learning framework for atomic simulations

NVIDIA ALCHEMI Toolkit is a GPU-first Python framework for building, running, and deploying AI-driven atomic simulation workflows. It provides a unified interface for machine-learned interatomic potentials (MLIPs), batched molecular dynamics, and composable multi-stage simulation pipelines: all designed for high throughput on NVIDIA GPUs.

Key Features

• Bring your own model — wrap any MLIP (MACE, AIMNet2, or your own) with a standard BaseModelMixin that handles input/output adaptation, capability negotiation via ModelCard, and runtime control via ModelConfig
• Graph-structured data — AtomicData and Batch provide Pydantic-backed, GPU-resident graph representations with built-in serialization to Zarr
• Composable dynamics — subclass BaseDynamics for custom integrators; compose stages with + (single-GPU FusedStage) or | (multi-GPU DistributedPipeline)
• Pluggable hook system — nine insertion points per step for logging, safety checks, enhanced sampling, profiling, and convergence detection
• Inflight batching — SizeAwareSampler replaces graduated samples on the fly, maximizing GPU utilization across long-running pipelines
• High-performance primitives — built on nvalchemi-toolkit-ops for GPU-optimized neighbor lists, dispersion, and electrostatics via NVIDIA warp-lang
• Agents as first-class citizens; includes core SKILLS.md library that teach agents how to use nvalchemi efficiently in agentic workflows. Simply copy the .claude/skills folder contents to your project repository or home directory depending on use case and agent platform (e.g. Claude Code, Cursor, OpenCode).

Example Snippets

Build atomic data and run a batched forward pass

import torch
from nvalchemi.data import AtomicData, Batch
from nvalchemi.models.demo import DemoModelWrapper

# Create two molecules
mol_a = AtomicData(
    positions=torch.randn(4, 3),
    atomic_numbers=torch.tensor([6, 6, 1, 1], dtype=torch.long),
)
mol_b = AtomicData(
    positions=torch.randn(3, 3),
    atomic_numbers=torch.tensor([8, 1, 1], dtype=torch.long),
)

# Batch for GPU-efficient inference
batch = Batch.from_data_list([mol_a, mol_b])

# Wrap a model and run
model = DemoModelWrapper()
outputs = model(batch)
print(outputs["energies"].shape)  # [2, 1] — one energy per system
print(outputs["forces"].shape)    # [7, 3] — one force vector per atom

Geometry optimization with convergence detection

from nvalchemi.dynamics import DemoDynamics, ConvergenceHook
from nvalchemi.dynamics.hooks import LoggingHook, NaNDetectorHook

dynamics = DemoDynamics(
    model=model,
    n_steps=10_000,
    dt=0.5,
    convergence_hook=ConvergenceHook.from_fmax(0.05),
    hooks=[LoggingHook(frequency=100), NaNDetectorHook()],
)
with dynamics:
    result = dynamics.run(batch)

Multi-stage pipeline: relax then MD (single GPU)

from nvalchemi.dynamics import DemoDynamics

optimizer = DemoDynamics(model=model, dt=0.5)
md = DemoDynamics(model=model, dt=1.0)

# + fuses stages: one forward pass, masked updates per sub-stage
fused = optimizer + md
with fused:
    fused.run(batch)

Distributed pipeline across GPUs

# Launch with: torchrun --nproc_per_node=2 my_pipeline.py
from nvalchemi.dynamics import DemoDynamics

optimizer = DemoDynamics(model=model, dt=0.5)
md = DemoDynamics(model=model, dt=1.0)

# | distributes stages: one dynamics per GPU rank
pipeline = optimizer | md
with pipeline:
    pipeline.run()

Installation

The quickest way to install:

pip install nvalchemi-toolkit

For development:

git clone https://github.com/NVIDIA/nvalchemi-toolkit.git
cd nvalchemi-toolkit
uv sync --all-extras

Optional extras:

pip install nvalchemi-toolkit[training]   # NVIDIA PhysicsNeMo integration
pip install nvalchemi-toolkit[mace]       # MACE model support

See the Installation Guide for Docker, Conda, and detailed setup instructions.

Contributions & Disclaimers

NVIDIA ALCHEMI Toolkit is in public beta. During this phase, the API is subject to change. Feature requests, bug reports, and general feedback are welcome via GitHub Issues.

License

Apache 2.0 — see LICENSE for details.