Rowan computes the electronic density of states (DOS) from periodic electronic-structure eigenvalues. Energies are shifted so that the Fermi level is at zero for metals, and the valence-band maximum is at zero for insulators and semiconductors.
The integration method depends on the dimensionality of the system.
For 3D crystals, Rowan uses the improved tetrahedron method (Blöchl–Jepsen–Andersen) on a full Monkhorst–Pack k-point grid. Tetrahedron integration is parameter-free and produces smooth, accurate DOS curves without introducing artificial broadening.
For 1D and 2D systems, Rowan uses Gaussian broadening, since tetrahedron integration requires a three-dimensional k-point mesh.