CASTEP

# Other Codes

This page contains a listing of third-party codes that are known to interoperate with CASTEP. Some of these programs require additional interface codes/scripts to take CASTEP output as their input, etc.

## Commercial Codes

BIOVIA Materials Studio is a suite of graphical tools and codes for quantum and classical simulation of materials, and is how CASTEP is distributed commercially.

## Other Tools

**Pre-processing Tools**

- c2x reads and writes a selection of file formats which relate to DFT electronic structure codes to perform manipulations and analysis. It can interpolate densities via a combination of trilinear and Fourier interpolation, integrate densities and calculate their dipole moments, and analyse bands for inversion symmetry. It can be used to produce output formats compatible with XCrysDen, VESTA, VMD and Jmol amongst others, and can also produce 1D data in a format suitable for gnuplot.
- CIF2Cell is a tool to generate the geometrical setup for various electronic structure codes from a CIF (Crystallographic Information Framework) file. Also supports supercell generation and formats for visualisation tools.
- SeeK-path is a k-path finder that provides band paths compatible with space group symmetry, and an interactive 3D visualiser.

**Post-processing Tools**

- Abins is a plugin for Mantid which allows scientists to compare experimental and theoretical inelastic neutron scattering spectra. AbINS uses the phonon data calculated by DFT programs, such as CASTEP, to generate an INS spectra of a powder sample, which makes it easier to establish a connection between theory and experiments.
- dispersion.pl and dos.pl are tools for producing band-structure and density of states plots from a CASTEP .bands file. They also support creating phonon dispersion and DOS plots.
- OCLIMAX is a free program for simulation of inelastic neutron scattering using vibrational frequencies and polarization vectors as input. It can perform simulations on both powder and single crystal samples, and the input phonon data can be obtained from first-principles or empirical calculations.
- OptaDOS is a code for calculating optical, core-level excitation spectra along with full, partial and joint electronic density of states (DOS).
- phonopy is an open source package for phonon calculations at harmonic and quasi-harmonic levels.
- phono3py calculates phonon-phonon interaction and related properties using the supercell approach. These properties include the lattice thermal conductivity, joint density of states and the phonon lifetimes.
- bs_sc2pc is a band structure unfolding tool for CASTEP. It implements the effective band structure method described by Popescu and Zunger doi:10.1103/PhysRevB.85.085201, and is distributed as part of the CASTEP academic distribution. Peter Brommer and David Quigley (2014) "Automated effective band structures for defective and mismatched supercells." J. Phys.: Condens. Matter 26 485501. Doi:10.1088/0953-8984/26/48/485501.

**Visualisation**

- CrystalMaker is a visualisation suite for designing and investigating crystal and molecular structures. It also provides support for modelling and animation of atomistic and electronic properties.
- JMOL is an open-source browser-based HTML5 viewer and stand-alone Java viewer for chemical structures in 3D with features for molecules, crystals, materials, and biomolecules.
- MagResView is a tool for visualization and processing of computed solid-state NMR parameters.
- OVITO is a scientific visualization and analysis software for atomistic and particle simulation data.
- VESTA is a 3D visualization program for structural models, volumetric data such as electron/nuclear densities, and crystal morphologies.
- XCrysDen is a crystalline and molecular structure visualisation program aiming at display of isosurfaces and contours, which can be superimposed on crystalline structures and interactively rotated and manipulated.

**Databases and Big Data**

- NOMAD supports CASTEP and its users. The service includes uploading, downloading, sharing, assigning DOIs, and more. Storing is guaranteed for at least 10 years, a requirement set by several funding agencies. The NOMAD Repository is also the only repository in Computational Materials Science that is recommended by NATURE Scientific Data. The repository currently contains over 10<sup>8</sup> entries - see the archive for the latest data.

**Structure Prediction**

- AIRSS(
*Ab initio Random Structure Searching*) is a very simple, yet powerful and highly parallel, approach to structure prediction. It generates random sensible structures and relaxes them to nearby minima. The sensible random structures are constructed so that they have reasonable densities, and atomic separations. Additionally they may embody crystallographic, chemical or prior experimental/computational knowledge. Beyond these explicit constraints the emphasis is on a broad, uniform, sampling of structure space. It is tightly integrated with CASTEP and has been used in a number of landmark studies to find novel phases of materials. - Calypso(
*Crystal structure AnaLYsis by Particle Swarm Optimization*) is an efficient structure prediction code. The approach requires only chemical compositions for a given compound to predict stable or metastable structures at given external conditions and can be used to predict/determine the crystal structure and design multi-functional materials. - USPEX (
*Universal Structure Predictor: Evolutionary Xtallography*) is a method developed by the Oganov laboratory for crystal structure prediction. It can very efficiently handle molecular crystals (including those with flexible and very complex molecules) and can predict stable chemical compositions and corresponding crystal structures, given just the names of the chemical elements. In addition to this fully non-empirical search, USPEX allows one to predict also a large set of robust metastable structures and perform several types of simulations using various degrees of prior knowledge. - XtalOPT is a free and truly open source evolutionary algorithm designed for a priori crystal structure prediction implemented as an extension to the Avogadro molecular editor.

**MD analysis**

- MDANSE (
*Molecular Dynamics Analysis for Neutron Scattering Experiments*) is a python application designed for computing properties that can be directly compared with neutron scattering experiments such as the coherent and incoherent intermediate scattering functions and their Fourier transforms, the elastic incoherent structure factor, the static coherent structure factor or the radial distribution function. - MOLDYN? is a generalized program for the evaluation of molecular dynamics models using nuclear magnetic resonance spin-relaxation data.
- MDTEP is a simple code for analysing MD trajectories and calculating thermodynamic properties such as the heat capacity and the velocity autocorrelation function.

**Transport**

- ShengBTE is a software package for solving the Boltzmann Transport Equation for phonons. Its main purpose is to compute the lattice contribution to the thermal conductivity of bulk crystalline solids, but nanowires can also be treated under a hypothesis of diffusive boundary conditions.
- AlmaBTE extends the ShengBTE approach currently employed for homogeneous bulk materials, into the mesoscale, to fully describe thermal transport from the electronic ab initio level, through the atomistic one, all the way into the mesoscopic structure level.
- BoltzTraP is a program for calculating the semi-classic transport coefficients.
- BoltzTrap2 is a modern implementation of the smoothed Fourier interpolation algorithm for electronic bands that formed the base of the original and widely used BoltzTraP code. One of the most typical uses of BoltzTraP is the calculation of thermoelectric transport coefficients as functions of temperature and chemical potential in the rigid-band picture. However, many other features are available, including 3D plots of Fermi surfaces based on the reconstructed bands.
- EMC(
*Effective Mass Calculator*) implements calculation of the effective masses at the bands extrema using finite difference method. There are two versions of the program: written in FORTRAN and Python. - Wannier90 is a tool for obtaining maximally-localised Wannier functions.

**Miscellaneous**

- ASE is a set of tools and Python modules for setting up, manipulating, running, visualizing and analyzing atomistic simulations. The code is freely available under the GNU LGPL license. It can interface with many different electronic structure codes.
- bader is a tool to perform Bader charge analysis on a charge density grid. Typically in molecular systems, the charge density reaches a minimum between atoms and this is a natural place to separate atoms from each other. Besides being an intuitive scheme for visualizing atoms in molecules, Bader's definition is often useful for charge analysis. For example, the charge enclosed within the Bader volume is a good approximation to the total electronic charge of an atom.
- ATAT (Alloy Theoretic Automated Toolkit) is a collection of alloy theory tools developed by Axel van de Walle.
- CASINO is a computer program system for performing quantum Monte Carlo (QMC) electronic structure calculations that has been developed by members of the Theory of Condensed Matter group in the Cambridge University physics department, and their collaborators, over more than 20 years. It is capable of calculating incredibly accurate solutions to the Schrödinger equation of quantum mechanics for realistic systems built from atoms.
- CellSymm is a simple C front-end for the spglib symmetry finding code. Its functionality has since been rolled into c2x.
- Emacs Mode is an emacs major mode for CASTEP input files with datatype based syntax highlighting and inbuilt help functionality.
- Soprano is a Python library meant to help crystallographers with the search and classification of new crystal forms for a given material. It provides a number of classes and functions to handle large amounts of candidate structures, compare them, sort them and cluster them.