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– EXX - Exact exchange
– SX - Screened exchange
– ZERO - No exchange-correlation potential
– HF-LDA -LDA with exchange contribution replaced by Hartree-Fock
– SHF-LDA - -LDA with exchange contribution replaced by screened Hartree-Fock
– EXX-LDA - -LDA with exchange contribution replaced by exact exchange
– SX-LDA - LDA with exchange contribution replaced by screeened exchange
• Electronic Minimization
– all-bands conjugate gradient minimizer for insulators
– Density-mixing minimizer for metals
– Ensemble DFT for metals
– Double-grid for charge densities
– Spin-polarized or unpolarized (paired electron) calculations
• Geometry Optimization
– Robust BFGS optimizer with line search
– Internal Co-ordinates optimizer for molecular systems
– Combined atomic/cell optimization using augmented Hessian
– Accurate variable-cell geometry optimization at fixed cutoff
– Damped MD
• Molecular Dynamics
– NVE and NVT ensemble MD simulation
– Accurate variable-cell MD at fixed cutoff
– Nose-Hoover chain thermostat
• Transition-State Searching
• Density-Functional Linear Response
– Phonon Spectra and Dispersion Curves.
– Dielectric permittivities (low frequency and optical)
– Born effective charges
– LO-TO splitting
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Input files
To run, CASTEP requires two input files plus one or two additional pseudopotential files for every element
included. The filenames of both input and output files begin with a common root, known as a “seed”,
making it easy to distinguish the files belonging to a particular run. To run it is merely necessary to
execute the command (either interactively or from a shell-script from a batch queue)
castep seed
where we assume that the executable is named castep and is found somewhere in the shell path.
The two input files are seed .cell which describes the simulation cell and its contents and seed .param
which describes the type of run to be performed and any options which may be required. (In fact
the seed .param may be omitted entirely in which case a single-point energy calculation with default
parameters is performed.)
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