postg2 is a sandbox program for trying different things with wfx/wfn
wavefunction files obtained from gas-phase quantum mechanical
calculations, mostly DFT.

The syntax is:

postg2 bleh.{wfx/wfn/tcfchk} command options

* info

  # Give some information about the wfn

  info

* xdm.f90 

  # Calculate the dispersion coefficients, XDM energy and derivatives

  xdm a1 a2 functional

* xdmc9.f90

  # Hack for 3-body coefficients and energies of water
  # trimers. Super-dirty, stay away.

* xyz.f90

  # Write the molecular geometry to standard output in the form of an 
  # xyz file.

  xyz

* atomicb.f90

  # Fun with the BR model in atoms. Nothing to see here. Move along,
  # citizen.  

* points.f90

  # Calculate a point using the selected property. See
  # properties_list.org for a list of those.

  {point/points} property <<eof
x1 y2 z2
...
eof

* line.f90

  # Calculate a line using the selected property

  line property x0 y0 z0 x1 y1 z1 npts

* plane.f90

  # Calculate a plane using the selected property

  plane property x0 y0 z0 x1 y1 z1 x2 y2 z2 n1 n2

* cube.f90

  # Calculate a cube using the selected property
  # (all units are angstroms)
  # You can use another cube as template for the grid. 

  cube property step
  cube property step x0 y0 z0 x1 y1 z1
  cube property other.cube
    
* cube_libxc.f90

  # Calculate the functional energy density on a cube.

  cube_libxc ix ic step
  cube_libxc ix ic step x0 y0 z0 x1 y1 z1 (bohr)
  cube_libxc ix ic other.cube

* energy.f90

  # Calculate the energy components

  energy ...
  ... charge (total charge)
  ... mocharge (charge in each MO, for debugging)
  ... ekin (kintic energy)
  ... enn (n-n coulomb energy)
  ... een (e-n coulomb energy -> has issues with the grid)
  ... eee (e-e coulomb energy)
  ... ebr (classic BR exchange)
  ... exx (exact exchange -> takes forever)
  ... libxc id (exc from libxc, with functional id.
                see properties_list.org)