ABC.DAT file : information on crystalline structure

 
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  This file is necessary for several programs :
               
               CONFNUC  (conformational angles)

               DSCAN    (all distances, etc..., calculations)

               CONTACTS (contacts between macromolecule and solvents)

               STATFO   (statistics on Fobs/Fcalc with PRFOUR.BIN)

               ORTHO    (orthogonalisation/deorthogonalisation)

               CHIRAL   (computes chiral volumes)

  Those programs read HD-type files for coordinate input (see NUCLIN.TXT)

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  It should contain :

       --- TITLE OF THE COMPOUND  (16A4)
       
        --- CELL PARAMETERS (ANGLES IN DEGREES) (6F8.2)

        --- NCENT, NEQV, NLATT (3I4)
           
           where    NCENT = 0 for non-centrosymmetric space group
                             1 for centrosymmetric space group

                     NEQV  = number of equivalent positions in space
                             group (as read from the Crystallographic Tables).
                             This does not include positions related by a 
                             center of inversion or lattice centering.

                     NLATT = lattice centering (0 = primitive, 1 = A centering,
                             2 = B, 3 = C, 4 = F, 5 = I, 6 = R, 7 = H)

        --- Equivalent positions (16 integers per position)

           The first integer is the sequence number for the position.
           The remaining 15 integers are designated IA, IB, ..., IO in
           the following formulae :

            NEWX = IA/IB + IC*X + ID*Y + IE*Z

            NEWY = IF/IG + IH*X + II*Y + IJ*Z

            NEWZ = IK/IL + IM*X + IN*Y + IO*Z
     
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