Field File - Periodic Fields (pscf_rpc and pscf_rpg)

Field File - 1D Fields (pscf_r1d) (Prev)         Command Files (Next)

The pscf_rpc and pscf_rpg programs are both designed to treat periodic structures, and use the same set of field file formats.

File Formats

The pscf_rpc and pscf_rpg programs can all read and write fields using following three field file formats:

• A basis file format contains the components for a representation of each field as a linear superposition of symmetry-adapated basis functions, in which each basis function is invariant under all of the elements of a specified space group.
• A r-grid file format contains the values of fields defined on the nodes of a regular grid.
• A k-grid file format that contains the discrete Fourier transform of fields defined on a regular grid.

Each of these file formats for periodic structures contains a header section that includes a information about the dimension of space, the crystal lattice system, unit cell parameters, and the number of monomer types, among other information.

The dimensions of the mesh used by the program that reads a file in r-grid or k-grid format (as given in the parameter file) must match the dimensions of the mesh used by the program that wrote the file (as declared in the field file header for these formats). The dimensions of this mesh are included in the header section of files written in r-grid and k-grid format.

The basis format is instead designed to allow users to change mesh dimensions: A instance of a program for which a particular list of mesh dimensions is declared in the parameter file can usually read and correctly intepret a field file that was created using a basis designed for a different mesh. The basis format can thus usually be used to change resolution by, for example, using a converged solution obtained with a coarse mesh as an initial guess for the solution on a refined mesh.

The current C++ version of PSCF can also read the basis and r-grid file formats used by the older Fortran PSCF program. The k-grid format used by the current version is not backwards compatible with the analogous k-grid format used by the Fortran program.

The names of some command-file commands that instruct pscf_rpc and pscf_rpg programs to read or write field files contain the strings "BASIS", "RGRID", or "KGRID" to indicate the use of a particular field file format.

Contents

The format of the header section and of the data section used by each field file type are described in more detail in the sub-pages linked below:

1. Field File Header
2. Basis Data Format
3. R-Grid Data Format
4. K-Grid Data Format

Field File - 1D Fields (pscf_r1d) (Prev)         Field Files (Up)         Command Files (Next)