# Amorphous Copper in the amorphous regime: random starting positions (no grain seeding) relaxed with weak bond + repulsion springs. The soft repulsion opens up a first-neighbour shell around 2.55 Å without imposing any angular order, giving a broad pair distribution characteristic of a metallic glass. Angle springs stay off so the angular distribution settles into the broad multimodal shape typical of a metallic glass. ## Parameters ```python from ase.build import bulk import tricor as tc atoms = bulk("Cu", "fcc", a=3.615) shell_target = tc.CoordinationShellTarget.from_atoms(atoms, phi_num_bins=90) cell = tc.Supercell.from_atoms( atoms, cell_dim_angstroms=(40, 40, 40), r_max=10, r_step=0.1, phi_num_bins=90, rng_seed=42, ) cell.generate( shell_target, num_steps=100, grain_size=None, bond_weight=0.35, angle_weight=0.0, repulsion_weight=0.85, hard_core_scale=0.88, nonbond_push_scale=0.60, ) ``` Angle springs are turned off so the angular distribution is shaped entirely by the competition between bond springs and repulsion. The result is a well-defined first neighbour shell with no medium-range crystallinity - characteristic of a metallic glass. ## Relaxation trajectory Interactive 3D viewer of the shell-relaxation trajectory (40 × 40 × 40 Å cell). Drag to rotate, scroll to zoom. Controls below the canvas play, scrub, and change playback speed. ## g3 distribution Measured from the **final (post-relaxation) atoms**. The heatmap is the reduced three-body density in units of the uniform random reference, where white = 1.0, blue = depleted, red = enhanced. The lower panel shows the pair profile g(r); the shaded amber band marks the first-neighbour shell used as the root-bond integration window for the g3 slice.