   parameter file                |   example (HOMO of benzene)
--------------------------------------------------------------------------------
   header text                   |   header C6H6_band_15
   inputfilename file            |   inputfilename C6H6.b_15.cube
   inputfileformat cube|xsf      |   inputfileformat cube
   outputfilename file           |   outputfilename C6H6.b_15.pov
   outputfileformat povray       |   outputfileformat povray
   isovalue (0.0,1.0)            |   isovalue 0.9
   sign positive|negative|both   |   sign both
   power 0|1|2                   |   power 1
   algorithm cube|tetrahedron    |   algorithm cube
   smooth T|F                    |   smooth T
   box T|F                       |   box F
   basis T|F                     |   basis F
   uc T|F                        |   uc F
   uco                           |   uco
   ucox ucoy ucoz                |   0.0 0.0 0.0
   ucv                           |   ucv
   ucv1x ucv1y ucv1z             |   1.0 0.0 0.0
   ucv2x ucv2y ucv2z             |   0.0 1.0 0.0
   ucv3x ucv3y ucv3z             |   0.0 0.0 1.0
   ucu bohr|angstrom|latvec      |   ucu latvec
   sc T|F                        |   sc T
   sco                           |   sco
   scox scoy scoz                |   -0.5 -0.5 -0.5
   scv                           |   scv
   scv1x scv1y scv1z             |   1.0 0.0 0.0
   scv2x scv2y scv2z             |   0.0 1.0 0.0
   scv3x scv3y scv3z             |   0.0 0.0 1.0
   scu bohr|angstrom|latvec      |   scu latvec
   sct T|F                       |   sct T

--------------------------------------------------------------------------------

   the isosurface is defined by isovalue * max |psi| for power = 0 and by
   integral_v |psi|^power = isovalue * integral |psi|^power for power > 0
   where psi is the scalar field and v is the volume inside the isosurface

   note that espresso already outputs |psi|^2, setting power = 2 yields
   |psi|^4 in this case, to produce |psi|^2 isosurface set power = 1

   algorithm stands for marching cubes and marching tetrahedra
   smooth defines whether to average normals for smooth rendering

   box specifies whether to generate supercell box in povray script
   basis specifies whether to generate coordinate axes in povray script

   sfo = scalar field origin    sfv = scalar field vectors
   uco = unit cell origin    ucv = unit cell vectors    ucu = unit cell units
   sco = supercell origin    scv = supercell vectors    scu = supercell units
   sct = supercell translational symmetry

   sfo/sfv are read from volumetric file

   if uc = T then uco/ucv are read from parameter file
             else uco/ucv are set to sfo/sfv
   if sc = T then sco/scv are read from parameter file
             else sco/scv are set to uco/ucv
   if uc = T and ucu = latvec then uco/ucv are scaled by sfv
   if sc = T and scu = latvec then sco/scv are scaled by ucv

   if sct = T then scv is used for translational symmetry
              else ucv is used for translational symmetry

   in most cases, set uc = F (uc = T is only needed if volumetric data
   do not span the whole unit cell and the supercell is being used, so
   the correct unit cell must be defined)

   use sc = T to construct the supercell spanning several unit cells or
   to assemble the unit cell around the origin of the coordinate system
   as in benzene example above (sco = (-0.5 -0.5 -0.5) in latvec units)

   the supercell may span a fractional number of unit cells, in this case
   set sct = F to produce the correct bonds at the faces of the supercell
