The CASTEP Properties task allows you to compute electronic, structural, and vibrational properties after the
completion of a single-point energy, geometry optimization, or dynamics run on a 3D periodic system.
In order to calculate properties using the CASTEP Properties task,
the results files from a suitable simulation must be present in the current project.
You can also use the Properties tab on the CASTEP Calculation dialog to
request that such properties be calculated as part of a CASTEP run. You can view the results using
the CASTEP Analysis dialog.
The properties that can be generated by CASTEP are:
- Band structure: Electronic eigenvalues along high symmetry directions in the Brillouin zone are calculated
non-self-consistently for both valence and conduction bands, using electronic charge densities and potentials generated during the
- Core level spectroscopy: Electronic energies on the Monkhorst-Pack mesh of k-points and the matrix elements
for electronic interband transitions are calculated, either with or without core holes.
- Density of states: Electronic eigenvalues on a fine Monkhorst-Pack grid
are calculated non-self-consistently for both valence and conduction bands, using electronic charge densities and potentials generated
during the simulation.
- Electron density difference: The electron density difference with respect to either a linear combination
of the atomic densities or a linear combination of the densities of sets of atoms contained in the structure is calculated.
- Electron localization function: A simple measure of electron localization in atomic and molecular systems.
- Electronic excitations: Electronic excitations for molecules in a box calculated using
the time-dependent density functional theory (TD-DFT).
- NMR: Chemical shielding tensors and electric field gradients are calculated.
NMR in CASTEP is part of the separately licensed module NMR CASTEP. NMR calculations can only be performed if
you have purchased this module.
- Optical properties: Matrix elements for electronic interband transitions
are calculated. The CASTEP Analysis dialog can be used to generate grid and chart documents containing
measurable optical properties.
- Orbitals: Information about electronic wavefunctions is provided. This allows you to visualize 3D
distribution of various electronic states (orbitals). This information is required also for visualization of STM profiles.
- Phonons: For phonon dispersion runs, phonon frequencies and eigenvectors along high symmetry directions in
the Brillouin zone are calculated. In the case of phonon density of states calculations, phonon frequencies and eigenvectors are
computed on a Monkhorst-Pack grid. This information is required during analysis to display total and projected (partial) phonon
densities of states. It is also used to calculate thermodynamic properties.
Phonon calculations take into account
existing fixed atom constraints, regardless of the overall Task
setting. Such fixed atoms are excluded from the calculation of vibrational properties,
which corresponds to the "partial Hessian" approach.
You must check the Fix fractional position checkbox on the
Atom tab of the Edit Constraints dialog, accessible from the
- Polarizability, IR and Raman spectra: The optical (ω = ∞) and dc (ω = 0) dielectric permittivity
or the optical (ω = ∞) and static (ω = 0) molecular polarizability, along with infrared or Raman intensities (response to an
electric field in the infrared range) are calculated. Permittivity is relevant for solid materials, while polarizability and infrared
intensities are relevant to molecules prepared using the supercell approach.
- Population analysis: Mulliken analysis and
Hirshfeld charge analysis is performed. Mulliken bond populations and
angular momentum-resolved atomic charges (as well as magnetic moments for spin-polarized calculations) are calculated. Optionally, the
weights required for partial density of states (PDOS) calculations are generated. Hirshfeld atomic charges are produced.
- Stress: The stress tensor is calculated and written to a
seedname.castep file. This
information is useful if, for example, you perform a geometry optimization run in which cell parameters are fixed and you want to check
how far the lattice is from equilibrium. For instance, a supercell study of a point defect should be carried out with the fixed cell
that corresponds to the theoretical ground state of the given system. The value of the stress after geometry optimization gives an
indication of the magnitude of the elastic effects associated with the supercell approximation.
Tasks in CASTEP
CASTEP Energy task
CASTEP Geometry Optimization task
CASTEP Dynamics task
CASTEP Elastic Constants task
CASTEP Transition State Search task
Setting up CASTEP calculations
Analyzing CASTEP results
Requesting electronic, structural, and vibrational properties
Accelrys Materials Studio 8.0 Help: Wednesday, December 17, 2014