v-ase-gui 0.0.64

v_ase: a Blender-style browser GUI and editor for ASE Atoms objects.

v_ase

v_ase was developed for researchers who want the convenience of ASE and the flexibility of Blender in one atomistic workflow. ASE is convenient because structures and trajectories can be opened directly from Python or the terminal. Blender is flexible because objects can be selected, moved, rotated, inspected, and edited in a real 3D scene. v_ase combines those two strengths: an ase gui-style entry point for scientific files, plus direct 3D editing for atomic structures.

It is intended to replace:

ase gui FILE

with:

v_ase gui FILE

For example:

v_ase gui
v_ase gui POSCAR
v_ase gui structure.vasp
v_ase gui movie.extxyz
v_ase gui relaxation.traj

Run v_ase gui without a filename to open an empty workspace, then use Open to choose an ASE structure, trajectory, or .vase project in the browser. A reader selector is available for ambiguous filenames, and a blocking loading overlay remains visible until the complete file is ready.

The viewer opens locally in your browser. By default, v_ase gui [FILE] starts in a lightweight visualization mode for fast inspection, trajectory playback, bonding, supercell preview, appearance edits, wrapping, and export. Add --interactive when you want Blender-style atom editing: left click and box drag select atoms, G moves atoms, R rotates atoms, X/Y/Z lock axes, and numeric input gives exact transforms. For normal blocking CLI use, closing the browser tab or window finalizes the current session and returns control to the terminal.

Highlights

• Open an empty file-loading workspace with v_ase gui, or open ASE structures, trajectories, and .vase projects directly with v_ase gui FILE or from v_ase.visualize import view.
• Inspect large systems in the lightweight default viewer, with GPU-instanced atoms, bonds, supercells, and live trajectory playback.
• Add --interactive for Blender-style selection, move, rotate, axis locking, numeric transforms, copy/paste, undo, and atom creation.
• Visualize and edit ASE constraints including FixAtoms, FixedLine, FixedPlane, FixScaled, and threshold-aware Hookean springs.
• Preview the exact output frame at the requested pixel aspect ratio, render with Modeling, Studio Sun, or Sun + Soft Shadow, then export images, video, POSCAR, a structure-only ASE pickle, or an editable Blender scene script.
• Save reusable visual presets as JSON or restore the complete scientific and visual working state from a portable .vase project.

Why v_ase

v_ase combines two workflows researchers normally have to keep separate:

ASE convenience	Blender flexibility	Scientific continuity
Open structures and trajectories from Python or the terminal.	Select, inspect, move, rotate, and style atoms directly in 3D.	Keep ASE cells, PBC, constraints, calculators, labels, and trajectory data connected to the visualization.

The default mode is a fast visualizer for routine inspection. Interactive mode adds structure editing only when it is needed, while the same appearance, bonding, measurement, trajectory, rendering, and export controls remain available in both workflows.

Feature Reference

• v_ase gui opens an empty workspace with browser file loading; v_ase gui FILE opens POSCAR, VASP, extxyz, traj, .vase, and other supported files directly.
• Blocking CLI sessions behave like ase gui: the terminal waits while the browser tab is open, then continues after the tab/window is closed.
• Python API for notebooks and scripts: from v_ase.visualize import view.
• Lightweight OVITO-style inspection is the default CLI mode, keeping bonds, supercell, appearance, visual type labels, measurements, projection, wrapping, and export controls responsive for large structures.
• Large scenes use shared unit-sphere geometry, GPU instancing for atoms, bonds, selection outlines, and supercell replicas, adaptive pixel ratio, and demand rendering. An idle viewport does not continuously consume GPU frames. See Rendering Performance for architecture and reproducible benchmark details.
• Orthographic projection is the default view, with perspective available from the View panel.
• The control panel is organized into Inspect, Structure, Display, and Output sections. It starts collapsed and opens from a compact edge handle, leaving the viewport unobstructed until controls are needed. v_ase remembers the active section, explicit collapsed state, and panel width. Tab opens the panel only while it is collapsed. Inside the panel, Tab remains normal form navigation; Esc commits the active field, closes the panel, and returns keyboard focus to the viewport. Controls inside each category start expanded.
• Viewport lighting is opt-in and its compact rendered-sphere control sits in the top toolbar, immediately beside the calculator controls. Its lit state adds a clear highlight and ground shadow, while the matte sphere remains recognizable as the same renderer control when lighting is off. Modeling keeps the original low-overhead, evenly-lit view; Studio Sun adds real-time PBR directional lighting; Sun + Soft Shadow adds a structure-fitted shadow map without a finite-frustum seam across large or off-origin structures. The Sun source and direction target are independently selectable viewport objects. Source + G translates the complete Sun rig without changing its direction; Target + G moves only the target to aim the light. R always rotates the target around the source, whichever handle is selected. Axis locks, numeric input, Enter, and Esc work for both handles. Source, target, and strength also remain editable in the lighting panel.
• Add --interactive for Blender-like atom editing: middle-mouse orbit, shift-middle pan, wheel zoom, click/box selection, G move, R rotate, axis locking, numeric transforms, Enter, Esc, copy/paste/undo/delete.
• Selection measurements: two selected atoms show distance, and three selected atoms show two distances plus the central angle. A compact persistent Measure HUD stays independent from the changing hover-atom metadata. In visualization mode, supercell replicas are independently selectable and their displayed Cartesian positions contribute to center, distance, and angle statistics.
• Calculator handling preserves existing ASE calculators, including SinglePointCalculator. The default lightweight visualization mode does not attach a fallback calculator; --interactive enables the soft repulsion fallback used for built-in relaxation.
• Torch is optional, not a package dependency. When torch is installed, the default repulsion calculator can use torch CPU or CUDA; otherwise it falls back to NumPy.
• ASE constraint-aware editing and visualization: FixAtoms, FixCartesian, FixedLine, FixedPlane, FixScaled, and Hookean. FixAtoms are rendered with a faceted, micro-etched material so they remain distinguishable without changing the element color. VASP selective-dynamics FixScaled masks are interpreted in fractional coordinates and displayed as cell-aware FixedPlane or FixedLine guides.
• Interactive constraint editing for selected atoms: apply or clear FixAtoms, FixedLine, and FixedPlane from the Constraints panel.
• Hookean constraints are visualized as threshold-aware hook/latch springs.
• Trajectory playback with live frame slider, FPS control, frame skip, image export, and video export.
• Interactive relaxation streams an optimization trajectory into the bottom timeline. Static single-structure sessions stay uncluttered until relaxation creates frames; loaded trajectory files keep their own movie timeline while a separate Relax row exposes the latest optimization path.
• Cell-local bonds, opt-in periodic-image bonds, label-pair cutoff tables, manual atom-index pairs, supercell preview, make_supercell(P) cell transform, and wrap atoms into cell. In interactive mode, auto and pairwise-cutoff bonds form and break live during G/R previews; the chosen mode, scales, pair-specific rcut values, MIC policy, and manual pairs persist when the structure or trajectory frame changes.
• Custom extxyz atom type labels such as H_type5 are preserved for GUI type settings even when ASE cannot parse them as real elements.
• LAMMPS lammpstrj and .data integer types stay visible as labels. Valid integer type ids are also used as atomic numbers for color/radius distinction; out-of-range ids fall back to ASE-valid H while preserving the raw label.
• Appearance label edits keep row order stable. Labels with element prefixes such as O_bridge automatically update the TYPE dropdown and default radius.
• Export POSCAR, a current-frame ASE pickle, PNG image, WebM video, and Blender Python scene script. The pickle preserves labels, cell/PBC, constraints, portable atom arrays, and valid SinglePointCalculator results, but excludes visualization settings and arbitrary executable calculator objects. Image export can preserve the complete live camera composition without crop or offset, or use a fixed px/Å scale for directly comparable images from different structures. Preview Area renders that same export camera and scene inside a screen-fixed frame whose aspect follows image W/H; orbiting or zooming changes the atoms inside the frame without moving the frame itself. Export-only atom smoothness and its quality multiplier are independent of viewport performance settings. Image export can also use viewport lighting or an independent Modeling, Studio Sun, or Sun + Soft Shadow setup. Blender export includes the viewport camera, unit cell, bonds, smooth atoms, and a true Blender SUN object with the same source position, target-derived direction, color, and numeric strength used in v_ase. Optimized export uses editable point groups and Geometry Nodes; individual atom objects remain available as an explicit export mode.
• Save Visual Settings as a reusable JSON preset. Matching labels recover their appearance and pairwise bond cutoffs, missing labels are ignored, and labels new to the opened structure receive ASE-derived defaults.
• Save a complete .vase project containing the current structure or trajectory, active frame, coordinates, cell, PBC, constraints, labels, portable atom arrays, cached calculator results, camera, lighting, bonds, quality settings, and supercell preview.

Installation

From PyPI

python -m pip install v_ase-gui

From GitHub

git clone https://github.com/lgyEthan/v_ase.git
cd v_ase
python -m pip install --upgrade pip
python -m pip install -e .

No conda and no Node.js are required. Three.js is vendored inside the package.

If pip reports ERROR: Error while checking for conflicts after saying Requirement already satisfied: v_ase-gui, the package is already installed; the failure is usually caused by a different installed package with broken metadata (version=None) in that Python environment. Use:

python -m pip install --upgrade pip
python -m pip install --upgrade --force-reinstall --no-deps v_ase-gui
python -m pip check

If pip check still crashes, create a clean virtual environment or repair the package with invalid metadata before installing scientific packages into that environment.

Quick Start

Open a structure file:

v_ase gui
v_ase gui POSCAR
v_ase gui structure.vasp
v_ase gui trajectory.extxyz
v_ase gui relaxation.traj
v_ase gui project.vase

The direct file form also works:

v_ase POSCAR

v_ase gui opens first and lets you choose a structure, trajectory, or .vase project from the Open button. The reader and ASE frame index can be selected before loading, including for an extensionless input.

Use from Python:

from ase.build import molecule
from v_ase.visualize import view

atoms = molecule("H2O")
edited = view(atoms)
print(edited.positions)

Useful CLI options:

v_ase gui structure.vasp --show-bonds
v_ase gui trajectory.extxyz --index :
v_ase gui trajectory.extxyz --index -1
v_ase gui ABCD --format POSCAR
v_ase gui ABCD --format XDATCAR
v_ase gui ABCD --format vasprun.xml
v_ase gui ABCD --format lammpstrj
v_ase gui ABCD --format data
v_ase gui ABCD --format vase
v_ase gui POSCAR --interactive
v_ase gui POSCAR --output edited.vasp
v_ase gui POSCAR --no-block

--format forces the input reader when the filename is ambiguous. It accepts common aliases such as POSCAR, XDATCAR, vasprun.xml, lammpstrj, traj, xyz, extxyz, data, and vase, plus raw ASE format names.

Example Structures

The README and demo structures can be regenerated from source:

python examples/readme_scenes.py

This writes single-structure .traj files under examples/readme_scene_assets/. Open them with normal v_ase commands:

v_ase gui examples/readme_scene_assets/fixedline.traj --show-bonds
v_ase gui examples/readme_scene_assets/fixedplane.traj --show-bonds
v_ase gui examples/readme_scene_assets/hookean.traj --show-bonds
v_ase gui examples/readme_scene_assets/ferrocene.traj --show-bonds
v_ase gui examples/readme_scene_assets/showcase.traj --show-bonds

Constraint guide design variants can be inspected without starting the app by opening docs/design/constraint_guides_preview.html in a browser. It compares five always-visible FixedLine marker candidates and five FixedPlane marker candidates on one constrained structure.

Case 1: Selection, FixedLine, and FixedPlane

Selected atoms get yellow Blender-style outlines. FixAtoms entries keep their atom color but switch to a faceted, micro-etched material, so they read as immobile without looking selected. FixedLine and FixedPlane guides stay hidden until the constrained atom is selected, then appear as a thin fading axis or a translucent CAD-style plane. When multiple FixedPlane atoms are selected, each atom keeps its own compact local plane marker so the constraint never looks anchored at the selection COM. Show Overlays can hide all of these guides for a clean structure view.

FixedLine is shown as a Li ion moving along a carbon nanotube channel. The ion can slide parallel to the tube axis, but not leave the channel direction:

FixedPlane is shown as a Li ion moving over a Cu(111) surface. The guide is an unbounded plane field through the selected atom, not a finite patch, so the surface-parallel XY constraint reads as diffusion over the surface rather than rotation:

Example:

from ase.build import molecule
from ase.constraints import FixAtoms, FixedLine, FixedPlane
from v_ase.visualize import view

atoms = molecule("H2O")
atoms.set_constraint([
    FixAtoms(indices=[0]),
    FixedLine(1, [1, 0, 0]),
    FixedPlane(2, [0, 0, 1]),
])

view(atoms)

When Apply constraints is enabled, move and rotate previews are projected onto the allowed line or plane and the backend commit uses atoms.set_positions(..., apply_constraint=True).

Case 2: Hookean Constraints

Hookean constraints are drawn with physical meaning. The rt threshold is placed in Angstroms along the constrained direction. Below the threshold the spring is inactive and shows slack. Beyond the threshold the latch engages and the spring becomes active. The example below uses a 9-atom ethanol-like adsorbate on Cu(111). The O-H group moves with oxygen while the C-O bond is pulled, so the graphic reads as a bond-retention constraint rather than an arbitrary long-range tether.

Example:

from ase.build import molecule
from ase.constraints import Hookean
from v_ase.visualize import view

atoms = molecule("H2O")
atoms.set_constraint(Hookean(0, 1, rt=1.15, k=5.0))
view(atoms)

For trajectories, the Hookean graphic updates frame by frame, so inactive, near-threshold, and active states can be inspected as a movie.

Case 3: Rotate and Move

Transforms follow Blender-style keyboard flow:

G X 1.2 Enter
R Z 30 Enter

Supported behavior:

• G: move selected atoms.
• R: rotate selected atoms.
• X, Y, Z: lock transform axis in transform mode.
• Numeric input: exact displacement or angle.
• Left click or Enter: confirm.
• Esc: cancel.
• Optional move increment in Angstrom.
• Optional rotate increment in degrees.
• Rotate pivots: selection center, global origin, or unit-cell center.
• Cell-boundary commensurate-angle guides for axis-locked 2D rotation.
• Optional magnetic snapping to low-strain integer-supercell matches.

Here a ferrocene molecule is used to show a selected cyclopentadienyl ring rotating about the X axis while the rest of the molecule remains in place:

For axis-locked rotation, the colored axis guide is drawn through the active pivot. If the pivot is the origin, the axis passes through the origin; if the pivot is the selection center of mass, it passes through that COM.

For periodic 2D cells, enable Commensurate guide and use R followed by an axis. v_ase compares integer supercell boundaries after removing their best rigid rotation, then draws candidate rays and keeps their angles in a compact CELL MATCHES strip that stays readable from every camera direction. The active ray is labelled in the viewport, while the Structure panel reports its principal boundary strain and area multiplier. Magnetic angle snap can pull the rotation into a candidate within a configurable angular range without blocking any other angle; the unchanged 0 deg identity is always a valid snap target. Hexagonal cells include the standard 21.7868 deg, 13.1736 deg, and 1.0501 deg commensurate series. The 1.0501 deg carbon marker is a TBG geometric reference near the electronic magic-angle regime, not an electronic-energy calculation. Equations and references are in the cell-aware rotation note.

Case 4: Bonds, Periodicity, and Supercells

Bonding can be automatic, label-pair based, or manually specified.

• Auto cutoff uses covalent radii.
• By default, bonds are drawn only when both endpoints are atoms displayed in the current cell. This avoids periodic bonds ending at invisible image atoms.
• Periodic image bonds enables minimum-image distances and draws bonds toward neighboring-cell images. This mirrors VESTA's boundary-search distinction between keeping a search inside the boundary and explicitly searching atoms beyond it.
• Pairwise cutoff exposes pair-specific rcut rows keyed by editable labels, so Cu_surface-Cu_bulk remains distinct even though both atoms are Cu. A cutoff of 0 disables that label pair immediately.
• Manual pair accepts explicit atom-index pairs such as 0-1, 1-2.
• During interactive G/R previews, auto and pairwise-cutoff pairs are re-inferred immediately. Manual pair topology remains fixed while its cylinders follow the moving atoms.
• Bond settings persist across transform commits, frame changes, structure refreshes, and atom-label edits.
• Bond appearance supports adjustable thickness, a lit 3D cylinder or camera-facing flat ribbon, and either one custom color or a midpoint split using the colors of the two bonded atoms. Custom and split colors are applied to the rendered bond materials, and the same settings are used by image, video, and Blender exports.
• Edited control values commit consistently when you press Enter, press Tab, or move focus to another control.
• Supercell preview shows full-opacity replicas, repeated unit-cell lines, and every currently visible bond in each repeated cell. In the default visualization mode, replicas support click, Shift-click, box selection, Ctrl+A, hover metadata, and displayed-coordinate measurements. In interactive mode they remain inspection-only and cannot enter an atom edit; Set Supercell as Cell converts them into real editable atoms.
• Set Supercell as Cell converts the preview into real editable atoms.
• Cell Transform accepts a full integer make_supercell(P) matrix.

For 2D periodic supercell/twist workflows, the cell transform applies:

H' = P H

to every trajectory frame. Non-periodic axes are protected from accidental mixing, tilting, or repetition.

Case 5: Trajectories

Multi-frame Atoms lists and ASE-readable trajectory files can be played as a movie.

v_ase gui relaxation.traj
v_ase gui movie.extxyz --index :

Controls:

• frame slider updates live while dragging
• play/pause button
• Space: play or pause
• FPS control updates immediately while playback is running
• Skip control advances by skip + 1 frames per playback tick while preserving the selected FPS
• export image and export video

Case 6: Custom Atom Types in extxyz and LAMMPS

Some workflows store type labels such as H_type5, O_type2, or Si_type1 inside the species column. ASE itself cannot treat these strings as chemical elements, so v_ase reads them as GUI atom types while mapping them internally to valid ASE base elements.

Example extxyz line:

H_type5 82.30128 7.97802 11.47478

In v_ase:

• ASE backend uses base element H.
• GUI labels remain H_type5.
• type-specific color variants are generated.
• Appearance radius controls are grouped by H_type5, O_type2, etc.
• Bond cutoff pair tables also use the preserved type labels.

For LAMMPS dump/data files, integer type ids are kept as GUI labels. If the type id is a valid atomic number, v_ase uses that element internally for default colors and radii:

• type=1 -> backend H, GUI label 1
• type=8 -> backend O, GUI label 8
• type=14 -> backend Si, GUI label 14

If a type id is outside the periodic table range, v_ase keeps the raw label and uses ASE-valid H internally so the structure can still be opened.

Case 7: Default Repulsion Calculator

If an input Atoms object already has a calculator, v_ase preserves and uses that calculator. This includes SinglePointCalculator results loaded from trajectory-style files and any calculator attached by the user before calling view().

In the default lightweight visualization mode, v_ase does not attach a fallback calculator and does not show calculator device controls. This keeps large-file inspection focused on rendering, bonding, supercell preview, wrapping, and export.

In --interactive, if no calculator is attached, v_ase installs a default soft repulsion calculator. The model applies harmonic pair repulsion below covalent-radius contact thresholds, so Relax can remove close contacts without requiring an external calculator. The top-right calculator controls are enabled only for this default calculator:

• DEVICE: CPU by default; CUDA is available when torch and CUDA are available in the current Python environment.
• CPU: number of CPU threads for torch CPU execution. The default is 4, capped by the machine CPU count.

Torch is intentionally not listed as a required dependency. If torch is absent, the repulsion calculator uses a NumPy implementation. Installing torch can make the default repulsion model faster, especially with CUDA hardware, but other ASE calculators remain fully user-defined and are not affected by these controls.

The repulsion calculator is also available as a normal ASE calculator from the public Python API:

from v_ase.calculators import RepulsionCalculator

atoms.calc = RepulsionCalculator(device="cpu", cpu_threads=4)

Convenience aliases are also provided for scripts that prefer shorter or compatibility-oriented imports:

from v_ase import RepulsionCalculator
from v_ase.calculator import RepulsionCalculator
from v_ase.repulsion import RepulsionCalculator

Conditioner is kept as an alias for the same calculator class, matching the reference model naming while still behaving like an ASE Calculator.

During relaxation, structure updates stream to the browser. In --interactive, if atoms are moved while relaxation is running, the current relaxation is stopped and restarted from the edited coordinates. The default visualization mode keeps atom editing and repulsion-calculator controls out of the UI.

Case 8: Export

From the right panel:

• Export POSCAR
• Export ASE Pickle
• Export Blender
• Preview Area
• Export Image
• Export Video

Image export provides its own resolution, transparency, grid, axes, physical scale, atom smoothness, and render-lighting controls. Current viewport preserves the live camera projection and complete composition; when the output aspect ratio differs, v_ase centers that view with margins instead of cropping or shifting it. Fixed physical scale uses pixels per Angstrom (px/Å), so the same value produces the same physical scale across different structures. For an output width W and scale s, the horizontal field is W / s Å. In perspective projection this scale is defined at the camera target plane; orthographic export has uniform scale at every depth.

Set image W and image H, then enable Preview Area to see the actual export camera rendered inside a fixed screen-space frame. The frame uses the requested pixel aspect ratio and the same scene, camera projection, centered margins, lighting, grid/axes policy, and atom-surface quality path as PNG export. Zooming changes the apparent atom size inside the frame while the frame remains fixed.

Atom smoothness selects the export sphere preset, and Smoothness scale multiplies its tessellation from 0.5× to 2.0×. Both affect only the PNG render, so a large scene can stay lightweight in the viewport while a publication image uses smoother atom surfaces. Studio Sun and soft-shadow images can likewise be exported without changing the viewport from Modeling mode.

Export ASE Pickle writes the current modified Atoms object for later Python use. Coordinates, chemical types, v_ase labels, cell/PBC, constraints, tags, charges, magnetic moments, and portable atom arrays remain attached. A calculator is included only when it is a still-valid SinglePointCalculator; live Python calculator implementations are deliberately omitted. The pickle does not contain camera, lighting, bonds, atom appearance, or other visual state.

Blender export downloads v_ase_blender_scene.py:

blender --python v_ase_blender_scene.py

Optimized instances is the default Blender atom mode. It emits one editable point mesh per visual label and uses Geometry Nodes to instance smooth icospheres, avoiding thousands of Python object-creation calls. Trajectories become point-mesh shape keys, bonds are grouped into multi-spline curves or combined flat meshes by material, and the unit cell is one multi-spline object. The Individual objects option remains available when every atom must be a separate Blender object.

Studio lighting is exported as a true Blender SUN parented to a source Empty and aimed at a target Empty. Source position, target-derived direction, RGB color, and numeric energy match the v_ase controls. Atom, bond, and cell colors use standard Principled BSDF nodes, so they remain colored in Blender Rendered mode. The active camera and projection are also reproduced.

The Python scene format works even when Blender is not installed in the Python environment running v_ase. Run the script in Blender and save it once to obtain a native .blend. OBJ is a poor primary interchange format here because it does not retain the camera, Sun rig, trajectory animation, constraints, instancing semantics, or the complete material setup.

Case 9: Save and Restore

The Output workspace separates three different operations:

• ASE Pickle (.pkl) stores the current ASE structure for Python reuse: coordinates, chemical types and labels, cell/PBC, constraints, portable atom arrays, and valid SinglePointCalculator results. It excludes visualization settings, the rest of a loaded trajectory, and arbitrary calculator objects.

• Visual Settings (.json) stores reusable presentation state: bond mode, pairwise cutoffs, manual pairs, bond material, label colors/radii/visibility, atom smoothness and anti-aliasing, camera/projection, grid/axes/cell, supercell preview, and Sun source/target/intensity. It does not store atomic coordinates. When applied to another structure, matching labels reuse saved values, absent labels are ignored, and newly encountered labels and bond pairs receive defaults.

• v_ase Project (.vase) stores the complete current project: all loaded trajectory frames, current frame, edited or wrapped coordinates, cell, PBC, ASE constraints, atom labels, portable per-atom arrays, JSON-compatible frame metadata, cached standard calculator results, and the complete visual setup.

Open a saved project directly:

v_ase gui research_state.vase

The same project can be selected from the browser Open command after starting an empty workspace with v_ase gui.

.vase is a validated ZIP container and does not unpickle arbitrary Python objects. Cached standard ASE results are restored through SinglePointCalculator. The built-in v_ase repulsion calculator is safely reconstructed from its numeric/string configuration so relaxation can resume; an arbitrary external calculator object is intentionally not embedded because it may contain executable code or machine-specific state.

Desktop Integration

The file format is ready for OS association, but pip install does not register a universal double-click handler. A packaged desktop launcher is required:

• macOS: an app bundle declaring the document type with CFBundleDocumentTypes.
• Windows: an installer registering a .vase ProgID and open command as described by Microsoft file-type registration.
• Linux desktops: a MIME definition, .desktop launcher, and association under the freedesktop MIME-apps specification.

macOS Finder Quick Look also requires a signed Quick Look preview extension for the custom content type. Apple supports view-controller or data-based custom previews, but an installed Python wheel alone cannot register one. The .vase archive therefore does not embed executable HTML; a future macOS app can add a read-only rotatable preview through Apple's QLPreviewingController.

Python API

from v_ase import view_edit, view_file

edited_atoms = view_edit(
    atoms,
    notebook=False,
    block=True,
    show_cell=True,
    show_axes=True,
    show_bonds=False,
    respect_constraints=True,
    allow_relax=True,
    return_mode="atoms",
)

view_file("trajectory.extxyz")

return_mode can be:

• "atoms": edited ASE Atoms
• "positions": edited Nx3 positions array
• "none": no return value

Controls

Input	Action
Left click	Select atom or confirm transform
Shift + left click	Add/remove selection
Left drag	Box select
Middle drag	Orbit viewport
Shift + middle drag	Pan viewport
Mouse wheel	Zoom
G	Move selected atoms or the selected Sun handle
R	Rotate selected atoms or rotate the Sun target around its source
X, Y, Z	Align view in select mode, lock axis in transform mode
Number keys	Numeric transform input
Enter	Confirm transform
Esc	Cancel transform; otherwise close an open control panel and return focus to the viewport
Ctrl+C / Ctrl+V	Copy / paste atoms
Ctrl+Z / Ctrl+Shift+Z	Undo / redo
Delete / Backspace	Delete selected atoms
Space	Play/pause trajectory
Tab	Open the control panel while it is collapsed; inside an open panel it remains normal form navigation
Sun source + G	Move the complete Sun rig (source and target)
Sun target + G	Aim the Sun by moving only its target
Either Sun handle + R	Rotate the target around the source

Notes

• The local editor server binds to 127.0.0.1.
• Relaxation uses the calculator already attached to the Atoms object. In --interactive, v_ase adds its default soft repulsion calculator only when no calculator is attached; visualization mode adds no calculator.
• Torch is optional. It is never required by pip install v_ase-gui, but when available it can accelerate the default repulsion calculator on CPU or CUDA.
• POSCAR exports a VASP structure. ASE Pickle exports the current Atoms with structural metadata and constraints; only valid SinglePointCalculator results are carried, and visualization settings are excluded.
• Visual Settings JSON is structure-independent presentation state. .vase is the full portable project state; it stores cached standard calculator results but not arbitrary executable calculator objects or undo history.
• The bundled browser UI is local-first; no Node.js build step is required.