C ================================================================== C !! !! C !! DDDDDDD IIII CCCCCC VV VV OOOOOO LL !! C !! DD DD II CC CC VV VV OO OO LL !! C !! DD DD II CC VV VV OO OO LL !! C !! DD DD II CC VV VV OO OO LL !! C !! DD DD II CC VV VV OO OO LL !! C !! DD DD II CC CC VVVV OO OO LL LL !! C !! DDDDDDD IIII CCCCCC VV OOOOOO LLLLLLLL !! C !! !! C ================================================================== C C TRIAL AND ERROR METHOD FOR THE AUTOMATIC INDEXING OF POWDER C PATTERNS - VARIATION OF PARAMETERS BY SUCCESSIVE DICHOTOMY. C THIS VERSION INCLUDES PARTITION OF VOLUME SPACE(01-1982) C THE FOLLOWING CRYSTALLINE SYSTEMS CAN BE EXAMINED : C CUBIC, QUADRATIC, HEXAGONAL, ORTHORHOMBIC AND MONOCLINIC SYSTEMS. C C FOR FURTHER INFORMATION CONTACT C D. LOUER C LABORATOIRE DE CRISTALLOCHIMIE C UNIVERSITE DE RENNES I C CAMPUS DE BEAULIEU C 35042 RENNES CEDEX -FRANCE- C TEL. 16-99-364815-(POSTE 2258) C C C --------------------------------------------------------------- C ! G E N E R A L I N S T R U C T I O N S ! C --------------------------------------------------------------- C C DICVOL PROPOSES SOLUTIONS; THE USER DISPOSES OF THEM. C THE AUTHORS DISCLAIM RESPONSIBILITY FOR ALL USE OF THIS C PROGRAM, WHETHER GOOD, BAD OR INDIFFERENT. C C DATA CARDS C ---------- C C CARD 1 TITLE FORMAT(16A4) C C C C CARD 2 N,ITYPE,JC,JT,JH,JO,JM FORMAT(7I2) C C N (COL. 1- 2) NUMBER OF LINES (E.G. 20). C ITYPE (COL. 4) SPACING DATA TYPE. C =1 THETA BRAGG IN DEGREES. C =2 2-THETA ANGLE IN DEGREES. C =3 D-SPACING IN ANGSTROMS. C =4 Q SPECIFIED IN Q-UNITS AS E+04/D**2. C JC (COL. 6) C =0 CUBIC SYSTEM IS NOT TESTED. C =1 CUBIC SYSTEM IS TESTED. C JT (COL. 8) C =0 TETRAGONAL SYSTEM IS NOT TESTED. C =1 TETRAGONAL SYSTEM IS TESTED. C JH (COL. 10) C =0 HEXAGONAL SYSTEM IS NOT TESTED. C =1 HEXAGONAL SYSTEM IS TESTED. C JO (COL. 12) C =0 ORTHORHOMBIC SYSTEM IS NOT TESTED. C =1 ORTHORHOMBIC SYSTEM IS TESTED. C JM (COL. 14) C =0 MONOCLINIC SYSTEM IS NOT TESTED. C =1 MONOCLINIC SYSTEM IS TESTED. C C C CARD 3 AMAX,BMAX,CMAX,VOLMIN,VOLMAX,BEMIN,BEMAX FORMAT(7F10.2) C C AMAX (COL. 1-10) MAXIMUM VALUE OF UNIT CELL DIMENSION A C IN ANGSTROMS. C BMAX (COL.11-20) MAXIMUM VALUE OF UNIT CELL DIMENSION B C IN ANGSTROMS. C CMAX (COL.21-30) MAXIMUM VALUE OF UNIT CELL DIMENSION C C IN ANGSTROMS. C VOLMIN(COL.31-40) MINIMUM VOLUME FOR TRIAL UNIT CELLS C IN ANGSTROMS**3. C VOLMAX(COL.41-50) MAXIMUM VOLUME FOR TRIAL UNIT CELLS C IN ANGSTROMS**3. C BEMIN (COL.51-60) MINIMUM ANGLE FOR UNIT CELL IN DEGREES C (DEFAULT= 90 DEGREES). C BEMAX (COL.61-70) MAXIMUM ANGLE FOR UNIT CELL IN DEGREES C (DEFAULT=130 DEGREES). C C C CARD 4 WAVE,POIMOL,DENS,DELDEN FORMAT(4F10.5) C C WAVE (COL. 1-10) WAVELENGTH IN ANGSTROMS. C POIMOL(COL.11-20) MOLECULAR WEIGHT OF ONE FORMULA UNIT IN C A.M.U. (DEFAULT =0.0 IF FORMULA WEIGHT C NOT KNOWN). C DENS (COL.21-30) MEASURED DENSITY IN G.CM(-3) C (DEFAULT =0.0 IF DENSITY NOT KNOWN). C DELDEN(COL.31-41) ABSOLUTE ERROR IN MEASURED DENSITY. C C C CARD 5 TO 5+N D(I),EPSIL(I) FORMAT(2F10.4) C C (ONE FOR EACH OBSERVED LINE, UP TO N) C D(I) (COL. 1-10) VALUE DESCRIBING THE OBSERVED POSITION C OF THIS LINE ACCORDING TO 'ITYPE'. C EPSIL (COL.11-20) ABSOLUTE ERROR IN 'D(I)', ACCORDING TO C 'ITYPE'. C C NOTE: C IF ITYPE=1,2,4 THE VALUES OF 'D(I)' AND 'EPSIL(I)' MUST C BE LISTED IN INCREASING ORDER. C IF ITYPE=3 THEY MUST BE IN DECREASING ORDER. C C REFERENCES: C 1.- LOUER, D. AND LOUER, M., METHODE D'ESSAIS ET ERREURS POUR C L'INDEXATION AUTOMATIQUE DES DIAGRAMMES DE POUDRE, C J. APPL. CRYST. 5,271-275(1972). C 2.- LOUER, D., SUCCESSIVE DICHOTOMY METHOD FOR INDEXING POWDER C PATTERNS, SYMPOSIUM ON ACCURACY IN POWDER DIFFRACTION, N.B.S. C GAITHERSBURG, MD., U.S.A., JUNE 11-15,1979. C 3.- C 4.- DE WOLFF, P. M., A SIMPLIFIED CRITERION FOR THE RELIABILITY C OF A POWDER PATTERN INDEXING, J. APPL. CRYST. 5,108-113(1968). C 5.- SMITH, G. S. AND SNYDER, R. L., F(N): A CRITERION FOR C RATING POWDER DIFFRACTION PATTERNS AND EVALUATING THE RELIABI- C LITY OF POWDER-PATTERN INDEXING, J. APPL. CRYST. 12,60-65 C (1979). C **************************************************************************** FROM PERSONAL CORRESPONDENCE WITH LOUER, THE FOLLOWING ADDITIONAL WAS LEARNED 1) INPUT DATA AS YOU KNOW, THE INDEXING PROBLEM NEEDS A HIGH ACCURACY ON THE POSITION OF THE DIFFRACTION LINES. SO, IT IS (STRONGLY) RECOMMENDED FOR INDEXING (AND ALSO IN DICVOL), THAT THE ABSOLUTE ERROR BE LOWER THAN 0.04 DEGREES 2 THETA. IN THE DATA THAT YOU SENT TO ME, THIS ERROR IS 0.20 DEGREES 2 THETA ON EACH LINE, WHICH IS NOT ACCEPTABLE. AS A CONSEQUENCE, YOUR OUTPUT GIVES A (VERY) GREAT NUMBER OF SOLUTIONS. FURTHERMORE, THE RECOMMENDED NUMBER OF LINES TO BE USED IS 20 (THE FIRST 20 OF THE PATTERN). YOU ARE USING 49 LINES, WHICH IS NOT NECESSARY AND INCREASES CONSIDERABLY THE CPU TIME. 2) STRATEGY THE DICHOTOMY METHOD (DICVOL) IS BASED ON THE SEARCH OF SOLUTION BEGINNING BY THE LOWEST VOLUMES--HOWEVER THE USER CAN SCAN THE VOLUME-SPACE AS HE WISHES. THE PRESENT PROGRAM STOPS THE SEARCH WHEN THE LOWEST VOLUMES ARE FOUND. SO, THE USER HAS SEVERAL POSSIBILITIES-- FIRST TO SCAN SUCCESSIVELY THROUGH THE DIFFERENT SYSTEMS (CUBIC,TETRAGONAL,HEXAGONAL...) BY DOMAINS OF 400 CUBIC ANGSTROMS. IN PRACTICE, IT IS BETTER TO ANALYZE THE LOWER SYMMETRIES FIRST, UP TO ORTHORHOMBIC, AND THEN RUN THE MONOCLINIC CASE (FOR WHICH AN ABSOLUTE ERROR OF 0.02 DEGREES 2 THETA IS RECOMMENDED). SECOND TO SCAN INDEPENDENTLY EACH SYSTEM (IF NECESSARY). IN THIS CASE, THE SOLUTION WITH THE LOWEST VOLUME WILL BE DISPLAYED FOR EACH SYSTEM, IF IT IS COMPATIBLE WITH THE INPUT LIMITS. IN ALL CASES, THE USER CAN KNOW THE VOLUME SPACE EXAMINED BY THE EXHAUSTIVE SEARCH OF THE DICHOTOMY METHOD. CONSEQUENTLY, IF NEW DOMAINS ARE NEEDED, NEW RUNS CAN BE PERFORMED WITH DIFFERENT LIMITS (VOLUMES). FROM MY EXPERIENCE BASED ON ABOUT 60 POWDER PATTERNS (MAINLY FROM NBS MONOGRAPHS) ONE RUN IS USUALLY SUFFICIENT FOR SYMMETRIES UP TO ORTHORHOMBIC. LETTER FROM D LOUER TO GERALD G JOHNSON JR. OCT 27, 1986