CASTEP 2.2 VARIABLES   (MJR)
   
  (maintainable by sort and grep)
 
CHDENG(NPLWV)		Recip. sp. charge density, indexing ??
CHDENR(NPLWV)		Real sp charge density. Sum of elements = NPLWV*NELECT
CPTWFP(NRPLWV,NBANDS)	The wave function at current k-point
DIRC(3,3)		Current real basis, DIRC(vector,components)
DIRI(3,3)		Initial real basis, DIRI(vector,components)
EXCDAT(2000)            XC data - should be increased to 20000
ICHARG(NSPEC)		Charge on each species 
ISYMM			Symmetrisation switch (0 = off, 1 = ON)
MPLWV			Size of work array for FFT routine
MPLWV		1	  >=NPLWV or >=NGX*NGY*(NGZ+1) depending on FFT routine
MAXCX,Y,Z		Real space Ewald sum parameters
MAXGPX,Y,Z		Recip. sp. Ewald sum parameters
MXRLNL			>=Max no of projectors in real space pot
MXRLSH			>=Max no of sph harm in real space pot (s=1,p=3,d=5)
NBANDS			No of bands to calculate
NBANOC			=NBANDS (always)
NDIM9                   >=NIONST (or 1 if ISYMM=0)
NDIM10			>=NKPTS  (or 1 if ISYMM=0)
NGPTAR(3)               NGX,NGY,NGZ
NGX			FFT grid
NGY			FFT grid
NGZ			FFT grid
NIONS			Max. no. of ions of one species
NIONSP(NSPEC)		No. of ions of each species
NIONST			Total no. of ions
NKPTS			No. k-points
NPLWV			NGX*NGY*NGZ (Number of PLane WaVes)
NPSPTS			No. of points in recip. space pseudopot.
NRGRPT			>=No. of grid points over which real space pot projects 
NRLPTS                  No. of points in real space potential
NRPLWV			>=No. plane waves in wavefunction
NSPEC			No. atomic species
POMASC(NIIONS*NSPEC)	Mass of each ion. Not used.
POMASS(NSPEC)           Mass of each species
POSIOL(3,NIONS,NSPEC)   Position of ions (unrelaxed)
POSION(3,NIONS,NSPEC)	Position of ions (relaxed)
RMOVE(NIONS*NSPEC)	Zero if ion fixed on relax, indexing ??
RMOVE0(NIONS*NSPEC)	??
VKPT(3,NKPTS)           k-point positions
WTKPT(NKPTS)		k-point weights
XCFDAT(2000)		XC data - should be increased to 20000
XCPDAT(2000)		XC data - should be increased to 20000