Den2Obj: A command-line tool for producing isosurfaces from electron density data files

Electron density is a foundational quantity in electronic structure calculations.It describes the spatial distribution of electrons in molecules and materials, and is used to derive key properties such as total energy, electrostatic potential, and atomic forces.Because electron density is a three-dimensional scalar field, specialized visualization techniques, including contour plotting, isosurface generation, and volumetric rendering, are needed to interpret bonding, reactivity, and electron redistribution.Den2Obj is a C++ command-line program for generating isosurfaces from electron density scalar fields.It supports input formats commonly used in electronic structure calculations, including CHGCAR and PARCHG files produced by VASP, as well as Gaussian Cube files.The resulting isosurfaces can be exported in widely supported geometry file formats, including STL (Stereolithography), PLY (Polygon File Format), and OBJ (Wavefront), enabling integration with visualization, rendering, and post-processing tools.In addition, Den2Obj can convert scalar fields to a documented native .d2oformat, a lossless binary container that stores the grid and unit-cell metadata while selecting an efficient compression method automatically.