Vasprunxml

vasprun.xml is an XML output file produced by the first-principles electronic-structure code VASP during a calculation. It contains a complete record of a run, including both electronic and ionic steps, structural information, and results. The file is designed to be machine readable and is widely used for post-processing and data extraction.

Avasprun.xml stores a wide range of information. It records input and run settings such as the k-points used, ENCUT, and the pseudopotentials employed, as well as lattice vectors and atomic coordinates for structures at each ionic step. It also captures electronic convergence data, the total energy, Fermi level, and forces and stresses for each relaxation step. In addition, the file can include electronic data such as band structure information, eigenvalues and occupations, and density of states including projected density of states whenever these are requested. Optional data such as charge density or other derived quantities may be included depending on the calculation setup and VASP version.

The file is a central resource for post-processing. It is read by tools and libraries such as pymatgen, ASE, sumo, and VASPKIT to extract energies, DOS, band structures, and structural snapshots, enabling reproducibility and data provenance. Because vasprun.xml can become very large for extensive calculations, parsing efficiency and storage considerations are important.

Version and compatibility notes: the exact XML schema and available data depend on the VASP version and build. Vasprun.xml is typically used alongside other VASP outputs (OUTCAR, CHGCAR, WAVECAR) to provide a comprehensive view of a calculation.