Molecular Orbitals¶

Render MO lobes from .cube or .cub files with --mo. The cube file contains both geometry and the orbital grid — no separate XYZ file needed.

When auto-orientation is active (default), the molecule is tilted 45° around the x-axis after alignment so lobes above and below the molecular plane are clearly visible. Use --no-orient to render in raw cube coordinates, or -I to use the v viewer for interactive orientation.

Cube files are typically generated by ORCA (orca_plot) or Gaussian (cubegen).

Python. All xyzrender flags below map 1:1 to keyword arguments on render() (--foo bar → foo="bar"). The non-obvious shapes here are --mo-colors POS NEG → mo_colors=("steelblue", "maroon") (a tuple) and loading a cube once for repeated renders with mol = load("homo.cube"). See the Python API guide.

from xyzrender import load, render

mol = load("caffeine_homo.cube")
render(mol, mo=True, output="caffeine_homo.svg")
render(mol, mo=True, iso=0.03, mo_colors=("maroon", "teal"), opacity=0.8)
render(mol, mo=True, surface_style="mesh")

HOMO (default)	LUMO (opaque + outlined)

The HOMO uses the default translucent appearance. The LUMO pairs --mo-outline-width with a high --opacity — outlines look cleanest on opaque lobes; at the default translucency the stroke fades along with the fill.

HOMO + H (iso 0.03)	HOMO rotation

xyzrender caffeine_homo.cube --mo -o caffeine_homo.svg
xyzrender caffeine_lumo.cube --mo --mo-colors maroon teal --opacity 0.8 --mo-outline-width 5 -o caffeine_lumo.svg
xyzrender caffeine_homo.cube --mo --hy --iso 0.03 -o homo_iso_hy.svg
xyzrender caffeine_homo.cube --mo --gif-rot -go caffeine_homo.gif

Surface styles¶

All contour-based surfaces (MO, density, NCI) support alternative rendering styles via --surface-style:

Mesh	Contour	Dot

xyzrender caffeine_homo.cube --mo --surface-style mesh
xyzrender caffeine_homo.cube --mo --surface-style contour
xyzrender caffeine_homo.cube --mo --surface-style dot

Style	Description
`solid` (default)	Filled surfaces with depth cueing
`mesh`	Warped grid lines emulating a 3D wireframe
`contour`	Iso-value contour rings showing surface depth
`dot`	Stippled contour rings (dots denser toward centre)

MO flags¶

Flag	Description
`--mo`	Enable MO lobe rendering (required for `.cube` or `.cub` input)
`--iso`	Isosurface threshold (default: 0.05 — smaller value = larger lobes)
`--opacity`	Surface opacity (default: 0.6 when `--mo` is active, otherwise 1.0)
`--surface-style STYLE`	Surface rendering style: `solid`, `mesh`, `contour`, `dot`
`--mo-colors POS NEG`	Lobe colors as hex or named color (default: `steelblue` `maroon`)
`--mo-outline-width PX`	Outline stroke per lobe (solid style only; pair with `--opacity 1.0` for crisp edges)
`--mo-outline-color COLOR`	Outline color (default: black)
`--flat-mo`	Disable depth-fog colour blend on MO lobes
`--mo-blur SIGMA`	Gaussian blur sigma for lobe smoothing (default: 0.8, ADVANCED)
`--mo-upsample N`	Upsample factor for contour resolution (default: 3, ADVANCED)