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Glossary

glim Glossary

Terminology index for glim research and development. Organized by domain.


Materials Science Terms

Potentials & Force Fields

Term Definition
EAM (Embedded Atom Method) Many-body potential commonly used for metals. Embedding function + pair terms.
MEAM (Modified EAM) Extension of EAM with angular dependencies.
ReaxFF (Reactive Force Field) Bond-order potential for reactive MD, handles bond formation/breaking.
Tersoff Bond-order potential for covalent materials (Si, C, Ge).
LAMMPS Large-scale Atomic/Molecular Massively Parallel Simulator — MD code.
MLIP (Machine Learning Interatomic Potential) Neural network potentials (DeePMD, MACE, NequIP) trained on DFT data.
DeePMD Deep learning potential with embedding networks.
MACE Equivariant message-passing neural network potential.
NequIP Neural Equivariant Interatomic Potentials.
FitSNAP Fitting SNAP potentials — spectral neighbor analysis potential.
SNAP Spectral Neighbor Analysis Potential.
ACE (Atomic Cluster Expansion) Framework for efficient atomic descriptors.

Simulation Methods

Term Definition
DFT (Density Functional Theory) Quantum mechanical method for electronic structure.
MD (Molecular Dynamics) Classical particle simulation using force fields.
PIMD (Path Integral MD) Quantum dynamics using ring polymers.
MC (Monte Carlo) Stochastic sampling method.
PBC (Periodic Boundary Conditions) Replicates simulation box infinitely.
NVE Microcanonical ensemble (constant N, V, E).
NVT Canonical ensemble (constant N, V, T).
NPT Isobaric-isothermal ensemble (constant N, P, T).

Analysis

Term Definition
RDF (Radial Distribution Function) g(r) — probability density of finding atoms at distance r.
MSD (Mean Squared Displacement) <Δr²(t)> — measures diffusion.
Coordination Number Number of nearest neighbors within cutoff.
Stress Tensor 3×3 matrix describing forces per unit area.
OVITO Visualization and analysis tool for MD (paid Pro version).
VMD Visual Molecular Dynamics — older visualization tool.

Benchmarks

Term Definition
Delta Codes DFT benchmark comparing total energies across elemental crystals.
Δ-factor RMS energy difference per atom vs. reference (target: <1 meV/atom).

LAMMPS Ecosystem

Term Definition
dump file LAMMPS output containing atomic positions per timestep.
lammpstrj Common dump file extension.
log file LAMMPS output containing thermodynamic data (temp, energy, etc.).
data file LAMMPS input file with initial configuration + topology.
thermo Thermodynamic output (Temperature, Energy, Pressure, etc.).
KOKKOS Performance portability library for GPUs/HPs in LAMMPS.
pair_style LAMMPS command specifying interaction potential.
fix LAMMPS command for perturbations, thermostats, etc.
compute LAMMPS command for calculating properties.
OpenKIM Open Knowledgebase of Interatomic Models.
Pizza.py Python toolkit for LAMMPS analysis (older).

glim Tech Stack

Web & Graphics

Term Definition
WebGPU Next-gen web graphics API with compute shaders.
WebGL Current web graphics API (no compute shaders).
WASM (WebAssembly) Binary format runnable in browsers at near-native speed.
wgsl WebGPU Shading Language.
R3F (React Three Fiber) React renderer for Three.js.
Three.js JavaScript 3D library.
Zustand Lightweight React state management.
Vite Fast JavaScript build tool.
Turbo (Turborepo) Monorepo build orchestration.

Rendering Techniques

Term Definition
Impostor spheres Render each atom as a quad; fragment shader raycasts sphere.
InstancedMesh Single draw call for many identical geometries.
Indirect draw GPU builds draw buffer; single draw call regardless of atom count.
Frustum culling Skip rendering atoms outside camera view.
SSAO (Screen Space Ambient Occlusion) Post-process darkening for depth perception.
DOF (Depth of Field) Blur based on distance from focus plane.
Bloom Glow effect for bright areas.
Tone mapping Map HDR colors to display range (ACES filmic).

Parsing

Term Definition
wasm-pack Build Rust → WASM with JS bindings.
wasm-bindgen Generate JS bindings from Rust.
Web Worker Background thread for parsing without blocking UI.
Streaming parser Process data incrementally without loading all into memory.

glim Project Structure

Term Definition
glimPSE WebGPU-powered LAMMPS visualization web app (current focus).
glimPSE The monorepo in atlas/glimPSE/.
@glim/core Shared types package.
@glim/parsers File parsing package (dump, log, data).
@glim/scene R3F scene components package.
@glim/renderer Low-level WebGPU pipeline package.
@glim/ui App shell and panels package.
@glim/web Vite app entry point.

File Extensions

Extension File Type
.lammpstrj LAMMPS dump file (text trajectory)
.dump Alternative dump file extension
.log LAMMPS log/thermo file
.data LAMMPS data file (initial config)
.lmp Alternative LAMMPS data extension
.wgsl WebGPU Shading Language
.tsx TypeScript React component
.rs Rust source file

See docs/navigation.md for codebase navigation. See docs/research-index.md for research document index. a