The output file of the xrefin map statement contains information about the unit cell, indexing of the map, and the actual electron density map. It can be read by a modified version of MAPPAGE to provide a ``DSN6'' file for FRODO. Modified versions of this program are included in the directory ``[.VAX.FRODOMAP]" for the VAX/VMS system and ``sgi/fft" for the SGI systems. The grid size of the map is determined by the GRID parameter in the FFT statement. The following is a FORTRAN example of how to read the formatted (QFORM=.TRUE.) or unformatted (QFORM=.FALSE.) version of the electron density maps:
C
C read title
IF (QFORM) THEN
READ(UNIT,'(/I8)',END=6,ERR=7) NTITLE
IF (NTITLE .LE. 0) THEN
READ( UNIT, '(A)',END=6,ERR=7)
ELSE
DO J = 1, NTITLE
TITLE(J) = ' '
READ (UNIT, '(A)',END=6,ERR=7) TITLE(J)
ENDDO
ENDIF
ELSE
DO J=1,MXTITL
TITLE(J)=' '
END DO
READ(UNIT,END=6,ERR=7) NTITLE,(TITLE(J)(1:80),J=1,NTITLE)
END IF
C
C read sectioning information
IF (QFORM) THEN
READ(U,'(9I8)',END=6,ERR=7)
& NA,AMIN,AMAX,NB,BMIN,BMAX,NC,CMIN,CMAX
ELSE
READ(U,END=6,ERR=7)
& NA,AMIN,AMAX,NB,BMIN,BMAX,NC,CMIN,CMAX
END IF
C
C read unit cell constants in angstroms and degrees
IF (QFORM) THEN
READ(U,'(6E12.5)',END=6,ERR=7) (CELL(I),I=1,6)
ELSE
READ(U,END=6,ERR=7) (CELL(I),I=1,6)
END IF
END IF
C
C read matrix mode
IF (QFORM) THEN
READ(U,'(3A)',END=6,ERR=7) MODE
ELSE
READ(U,END=6,ERR=7) MODE
END IF
IF (MODE.NE.'ZYX') THEN
CALL WRNDIE(-5,'RMAP','error in matrix mode')
GOTO 7
END IF
C
C read density matrix, c is slowest ("z-sections").
DO C=CMIN,CMAX
C
C read next section
IF (QFORM) THEN
READ(U,'(I8)',END=6,ERR=7) KSECT
READ(U,'(6E12.5)',END=6,ERR=7)
& ((MAP(A,B,C),A=AMIN,AMAX),B=BMIN,BMAX)
ELSE
READ(U,END=6,ERR=7) KSECT
READ(U,END=6,ERR=7)
& ((MAP(A,B,C),A=AMIN,AMAX),B=BMIN,BMAX)
END IF
END DO
The following lines show the beginning of a typical electron
density map file:
2 !NTITLE
REMARKS FILENAME=""
REMARKS DATE:18-Jun-90 12:24:08 created by user:
XMAP: extend NA=( 30 4 12) NB=( 15 5 10) NC=( 16 2 12)
30 4 12 15 5 10 16 2 12
XMAP: a= 40.96, b= 18.65, c= 22.52, alpha= 90.00, beta= 90.77, gamma= 90.00
0.40960E+02 0.18650E+02 0.22520E+02 0.90000E+02 0.90770E+02 0.90000E+02
XMAP: written in ZYX mode (z-sections)
ZYX
XMAP: section # 0 average density=-0.336 sigma= 0.907
0
-0.97086E+00-0.49927E+00-0.82774E+00-0.13491E+01-0.57034E+00-0.71253E-01
-0.19491E+00 0.61017E+00 0.10064E+01-0.22888E+01-0.94020E+00 0.77451E+00
0.57539E+00-0.31211E-01-0.27430E+00-0.36526E+00 0.34772E+00 0.81884E+00
-0.19954E+01-0.10117E+01 0.18038E+01 0.19008E+01 0.11886E+00-0.41646E+00
0.47560E-01 0.48855E+00 0.57606E+00-0.22320E+00-0.12787E+01 0.47590E+00