Momentum
The momentum of a particle is a vector defined as its mass times its velocity.
Predictions of momenta can be used, for example, to predict a future step in
molecular dynamics (see, e.g., https://arxiv.org/pdf/2505.19350).
In metatomic models, they are associated with the "momentum" or
"momentum/<variant>" name (see Variants), and must have the
following metadata:
Metadata for "momentum"
Metadata |
Names |
Description |
|---|
keys |
"_"
|
the keys must have a single dimension named "_", with a single entry
set to 0. The "momentum" quantity is always represented as a
metatensor.torch.TensorMap with a single block. |
samples |
["system", "atom"]
|
the samples must be named ["system", "atom"], since "momentum" is
always per-atom.
"system" must range from 0 to the number of systems given as input
to the model. "atom" must range between 0 and the number of
atoms/particles in the corresponding system. If selected_atoms is
provided, then only the selected atoms for each system should be part of
the samples.
|
components |
"xyz"
|
The "momentum" quantity must have a single component dimension named
"xyz", with three entries set to 0, 1, and 2. The momentum
is always a 3D vector, and the order of the components is x, y, z. |
properties |
"momentum"
|
The "momentum" quantity must have a single property dimension named
"momentum", with a single entry set to 0. |
The following simulation engine can provide "momentum" as inputs to the
models:
