VelocityAutoCorrelation

class torch_sim.properties.correlations.VelocityAutoCorrelation(*, window_size, device, use_running_average=True, normalize=True)

Bases: object

Calculator for velocity autocorrelation function (VACF).

Computes VACF by averaging over atoms and dimensions, with optional running average across correlation windows.

Using VelocityAutoCorrelation with TrajectoryReporter:

# Create VACF calculator
vacf_calc = VelocityAutoCorrelation(
    window_size=100,
    device=device,
    use_running_average=True,
)

# Set up trajectory reporter
reporter = TrajectoryReporter(
    "simulation_vacf.h5",
    state_frequency=100,
    prop_calculators={10: {"vacf": vacf_calc}},
)

Parameters:

• window_size (int)

• device (device)

• use_running_average (bool)

• normalize (bool)

property vacf: Tensor | None

Current VACF result.