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Output Files

CASTEP writes output data in a variety of files. Some of these will be in human readable ASCII format (i.e. plaintext) and can be read with commands such as less or more on linux, or with a simple text editor (textedit, notepad etc). Other files will be in binary format and are designed to be read or processed with an external program. See Tools for software and libraries to read and analyse them.

Groundstate

  • .castep ASCII. CASTEP's main outputfile.

  • .bib ASCII. Bibtex file containing citations to the methods CASTEP has used in the calculation.

  • .check Binary. This checkpoint file contains the results of the calculation including the groundstate charge density and wavefunctions. It is typically a very large file. Will be read by CASTEP when performing a continuation calculation. Also read by postprocessing software such as c2x or euphonic.

  • .check_bak Binary. backup of the checkpoint file.

  • .castep_bin Binary. This file is identical to .check except that does not contain the wavefunctions. Therefore it is usually much smaller than the .check file, making it suitable for archiving a calculation. It may also be processed by euphonic, c2x or other software which can read checkpoint file.

  • .cst_esp Binary. The local part of the Kohn-Sham potential (Vloc + Hartree + XC).

  • .usp ASCII. Pseudoptential data, written for each species. See the page on reading usp headers.

  • .uspso ASCII. Pseudoptential data, written for each species. This is the J-dependant version of the .usp. See the page on reading usp headers.

  • .beta Xmgrace (.agr) format. Beta projectors for each generated pseudopotential. Only written if a test configuration [] is present in the OTF string.

  • .pwave Xmgrace (.agr) format. Pseudo-wavefunctions for each generated pseudopotential. Only written if a test configuration [] is present in the OTF string.

  • .econv Xmgrace (.agr) format. Isolated atom energy cutoff convergence for each generated pseudopotential. Only written if a test configuration [] is present in the OTF string.

  • .bands ASCII. Kohn-Sham eigenvalues at the requested k-points. Can be used to plot band structures or density of states. Note that the eigenvalues are given in atomic units (Hartree).

  • .den_fmt ASCII. Charge density. Only written if write_formatted_density : T.

  • .pot_fmt ASCII. Groundstate local potential (Vloc + Hartree + XC) (See .cst_esp). Only written if write_formatted_potential : T.

  • .chdiff Binary. Difference between the groundstate charge density and a superposition of atomic densities. Only written if calculate_densdiff : T

  • .chdiff_fmt ASCII. same data as .chdiff in human readable format. Only written if calculate_densdiff : T and write_formatted_density : T.

  • .xrd_sf ASCII. X-ray structure factors. See the documentation page.

  • .elf Binary. Result of ELF calculation.

  • .elf_fmt ASCII. Result of ELF calculation.Only written if write_formatted_elf : T.

Geometry Optimisation

  • *.geom ASCII. State of the system (coordinates, unit cell etc) at each step of the geometry optimisation. See for specification. Can be used to animate the geometry optimisation and can be read directly by Jmol.

Molecular Dynamics

  • *.md ASCII. State of the system (coordinates, unit cell etc) at each step of the molecular dynamics simulation. Same format as the .geom file. See for specification. Can be used to animate the trajectory, and can be read directly by Jmol.

  • *.hug ASCII. Hugoniot data for hugoniostat MD.

Spectral

  • .pdos_bin Binary. Matrix elements used for plotting a projected density of states. Used by Optados.

  • .ome_bin Binary. Matrix elements used for calculating optical properties. Used by Optados.

  • .dome_bin Binary. Diagonal elements of the optical matrix elements. Used by Optados to plot densities of states / spectral properties using adaptive smearing.

  • .elnes_bin Binary. Matrix elements used for plotting the core-loss spectrum. Used by Optados.

  • .orbitals Binary. Kohn-Sham states at each kpoints. Used by orbital2bands to make a reorganised .bands file for a cleaner looking bandstructure.

Phonon and Efield

  • .phonon ASCII. Phonon eigenvalues and eigenvectors.

  • .phonon_dos ASCII. Phonon branch gradients and density-of-states when param keyword phonon_calculate_dos is true.

  • .efield ASCII. Mode oscillator strengths and frequency-dependent permittivity tensor in the ir band.

Electron-Phonon coupling

  • .epme ASCII. Electron-phonon matrix elements.

  • .epme_bin Binary. Electron-phonon matrix elements.

Elastic Constants

  • .elastic ASCII. Elastic constants, compliance matrix, Frozen ion constants, Internal Strain and Piezoelectric tensors

TDDFT

  • .tddft ASCII. TDDFT state band projection analysis and TDDFT excitation energies.

Magres

  • .magres ASCII. Contain the NMR tensors (depending on magres_task shielding, EFG or J). Read by MagresView or the Soprano python libraries.

  • _current.dat ASCII. Written if MAGRES_WRITE_RESPONSE=True. Used to compute NICS (nucleus independent chemical shifts) see https://www.ccpnc.ac.uk/docs/nics .