Vector plots

The information needed for vector plots is in the file “jvec.{vti,vtu}” and can be visualised using ParaView (

For the visualisation of the current vector field we use two different file formats. ‘vti’/ImageData for grids that consist of orthogonal basis vectors in two or three dimensions and evenly spaced grid points, and ‘vtu’/UnstructuredGrid for arbitrary sets of points. vti/vtu files consist of nodes (grid points) and cells. In vti files the node positions are defined by a range and spacing in each dimension and the (cuboid) cells are defined implicitly. In vtu files, the grid point coordinates are given explicitly and each cell is defined by a cell type (10 for tetrahedral) and the indices of the defining nodes. For each node we write down a vector (the induced current) while the cells are not assigned a value for typical visualisations (ie, the value can be set to 0.0). However, cells need to be defined—paraview interpolates the values given at grid points within each cell.

In case of vti files, all required information is given by the grid and no further input is required.

In case of vtu files we require an external program to create a tetrahedral mesh. One choice for such a program is TetGen ( The workflow is:

1. obtain a grid of your choice. The file format should be: no header entries, each line contains xyz of a grid point. That is, the number of lines equals the number of grid points. A grid can for example be obtained from the numgrid library (but those grids will typically be more expensive than necessary for visualisation purposes), or by writing a short script to generate a custom grid for a class of molecules. A universally useful grid can be generated with the provided script ‘’.

2. run ‘ <grid file>’ to obtain ‘grid.node’ which can be read by tetgen.

3. run ‘tetgen grid.node’ to obtain ‘grid.1.ele’. This file contains one quadruple of indices for each tetrahedral cell.

4. run your gimic job to obtain ‘jvec.vtu’. The generated ‘grid.1.ele’ is read automatically.

(What we cannot do yet: it might for some systems be useful to visualise properties not in a volume but on a surface, as for example the surface of a fullerene. This can also be done using vtu-files, but one needs to write a new output routine. For that it will be required to find the cell type of a triangle, and find the ‘tetgen’ command for 2D Delaunay triangulations. ETA: one day.)

Check also the section on the interpretation of GIMIC results and the Youtube examples.


Follow the instructions under /examples/benzene/ParaView-README

File needed: “jvec.vti” Note, you need to generate your own molecule file, eg. in cml format, which is readable in ParaView. You can use for example Avogadro ( and read in and export it to mol.cml. Then you need to convert the mol.cml file to bohr.

Note that animations are also possible using ParaView.

(Signed) modulus density plots

This is possible with ParaView using the file “jmod.vti”.

ACID plots

This is possible with ParaView using the file “acid.vti”.