Geometric Dump Sequence Generator

A Data Bottleneck

Studying glassy systems requires capturing dynamics across many orders of magnitude in time. To understand both fast and slow processes, we'd ideally record at high temporal resolution. However, doing so over the enormous timescales where glasses are dynamically interesting creates a storage bottleneck.

Why not linear dumping?

• Linearly-spaced dumps at high resolution generate impractical amounts of data
• Low-resolution linear dumps miss fast dynamics entirely
• Example (low temperature): Capturing 8 decades of time (10⁰ to 10⁸ timesteps) at high resolution would require ~10⁸ frames. With 100,000 particles at ~12 bytes/particle/frame, that's ~120 TB per run. For 5 independent runs (statistical significance), you'd need ~600 TB of storage, and that's just for one temperature!

The Geometric Solution

Geometric spacing (t_n = t₀ · rⁿ) solves this by providing:

• High density at short times → captures fast dynamics
• Lower density at long times → captures slow dynamics efficiently
• Uniform coverage on a log-time axis
• Typically ~9,000 dumps to span 8 decades with repeated sequences
• Example (low temperature): Using ~9,000 dumps: 9,000 × 1.2 MB ≈ 11 GB per run, or ~55 GB for 5 runs. That's about 11,000× less storage than linear dumping!

Repeated Geometric Sequence Approach

For typical analysis of equilibrated systems, we use repeated short geometric sequences. This preserves time-translation invariance (TTI) in two-time correlation measurements, allowing us to select short or long lag times (τ) without being restricted to fixed high temporal resolution.

For studying aging effects, we add a long geometric sequence during the equilibration/aging period to capture the system's evolution.

About This Tool

This tool was created by Max Meinke and adabted for the web by Collin. It generates utility files (dump_times.txt, run_times.txt, file_names.txt) to be looped over in LAMMPS for saving trajectory data following this geometric dump schedule.