calculation¶

Provide refinement functions for a the raw data of a VASP calculation run in the current directory.

Usually one is not directly interested in the raw data that is produced but wants to produce either a figure for a publication or some post-processing of the data. This package contains multiple modules that enable these kinds of workflows by extracting the relevant data from the HDF5 file and transforming them into an accessible format. The modules also provide plotting functionality to get a quick insight about the data, which can then be refined either within python or a different tool to obtain publication-quality figures.

Generally, all modules provide a read function that extracts the data from the HDF5 file and puts it into a Python dictionary. Where it makes sense in addition a plot function is available that converts the data into a figure for Jupyter notebooks. In addition, data conversion routines to_X may be available transforming the data into another format or file, which may be useful to generate plots with tools other than Python. For the specifics, please refer to the documentation of the individual modules.

The raw data is read from the current directory. The Calculation class provides a more flexible interface with which you can determine the source directory or file for the VASP calculation manually. That class exposes functions of the modules as methods of attributes, i.e., the two following examples are equivalent:

using calculation module

>>> from py4vasp import calculation
>>> calculation.dos.read()

using Calculation class

>>> from py4vasp import Calculation
>>> calc = Calculation.from_path(".")
>>> calc.dos.read()

In the latter example, you can change the path from which the data is extracted.

Attributes

`band`	The band structure contains the k point resolved eigenvalues.
`bandgap`	This class describes the band extrema during the relaxation or MD simulation.
`born_effective_charge`	The Born effective charge tensors couple electric field and atomic displacement.
`CONTCAR`	CONTCAR contains structural restart-data after a relaxation or MD simulation.
`density`	This class accesses various densities (charge, magnetization, ...) of VASP.
`dielectric_function`	The dielectric function describes the material response to an electric field.
`dielectric_tensor`	The dielectric tensor is the static limit of the `dielectric function`.
`dos`	The density of states (DOS) describes the number of states per energy.
`elastic_modulus`	The elastic modulus is the second derivative of the energy with respect to strain.
`energy`	The energy data for one or several steps of a relaxation or MD simulation.
`fatband`	BSE fatbands illustrate the excitonic properties of materials.
`force`	The forces determine the path of the atoms in a trajectory.
`force_constant`	Force constants are the 2nd derivatives of the energy with respect to displacement.
`internal_strain`	The internal strain is the derivative of energy with respect to displacement and strain.
`kpoint`	The k-point mesh used in the VASP calculation.
`magnetism`	The local moments describe the charge and magnetization near an atom.
`pair_correlation`	The pair-correlation function measures the distribution of atoms.
`phonon_band`	The phonon band structure contains the q-resolved phonon eigenvalues.
`phonon_dos`	The phonon density of states (DOS) describes the number of modes per energy.
`piezoelectric_tensor`	The piezoelectric tensor is the derivative of the energy with respect to strain and field.
`polarization`	The static polarization describes the electric dipole moment per unit volume.
`potential`	The local potential describes the interactions between electrons and ions.
`projector`	The projectors used for atom and orbital resolved quantities.
`stress`	The stress describes the force acting on the shape of the unit cell.
`structure`	The structure contains the unit cell and the position of all ions within.
`system`	The SYSTEM tag in the INCAR file is a title you choose for a VASP calculation.
`topology`	The topology of the crystal describes the ions of a crystal and their connectivity.
`velocity`	The velocities describe the ionic motion during an MD simulation.
`workfunction`	The workfunction describes the energy required to remove an electron to the vacuum.