moltui 0.2.3

Terminal-based 3D molecular viewer

MolTUI

MolTUI is a terminal molecular viewer for the XYZ, Zmat, Molden, Gaussian Cube and ORCA GBW file format designed for quick inspection of geometries and orbitals directly in the terminal using Unicode characters. Ideal for remote SSH sessions and lightweight analyses.

Installation

pip install moltui
# or
uv tool install moltui

Usage

moltui <file>

Features

Visualize Orbitals

• The rendering of orbitals can be toggled via o.
• Molden and GBW files can contain multiple molecular orbitals. Toggle the orbital sidebar with m. Cycle through MOs with next and prev (or via [ and ] even when the sidebar is hidden).

Analyze Geometry

• Bond lengths, angles and dihedrals can be viewed using the geomtry key which opens a sidebar. Navigate between tabs via <tab>.
• The quantity is highlighted in yellow on the molecule.
• Sort the quantity in ascending order via s.
• Atom indices can be toggled via #.

Export to PNG Format

The e key exports the current scene to a PNG.

Tune Visuals

The V key opens a sidebar where the isovalue, molecule style and lighting can be modified.

The lower case v cycles between the styles.

CPK	Licorice	VDW

Toggle between light and dark mode with i.

Light	Dark

Supported formats

• Structures Only: XYZ, Gaussian ZMAT.
• Structures and Orbitals: Molden, Gaussian Cube, Orca GBW¹.

¹ Requires orca_2mkl in PATH

Keybindings

Navigation

Key	Action
h/j/k/l or arrows	Rotate left/down/up/right
,/.	Roll clockwise/counter-clockwise
J/K or +/-	Zoom out/in
t	Toggle pan/rotation mode
c	Center view
r	Reset view

Display

Key	Action
o	Toggle orbital isosurfaces
i	Toggle dark/light theme
b	Toggle bonds
e	Export PNG
v	Toggle style (CPK, Licorice, VDW)
#	Toggle atom numbers

Panels

Key	Action
g	Geometry panel (bonds, angles, dihedrals)
m	MO panel (molecular orbitals)
V	Visual settings panel (style, sizes, lighting)
[, ]	Previous/next MO
n/p	Navigate panel entries
Esc	Close panel

Visual panel

Key	Action
n/p	Move between controls
Tab/Shift+Tab	Adjust value (slider) or switch option (style)

General

Key	Action
q	Quit

Limitations

• The content is rendered using braille Unicode characters and, therefore, the quality of rendering can depend on the font and terminal emulator. All figures in the repository have been generated using the JetBrains Mono Nerd Font in the Kitty terminal.
• The Orca GBW file format is typically incompatible between versions. Therefore, the orca_2mkl should ideally be of the same version as the Orca version used to produce the GBW file. Newer version of Orca can try to recover earlier GBW files using the rescue feature.