C ******************************************************************* C ** FICHE F.27 ** C ** CALCULATION OF TIME CORRELATION FUNCTIONS. ** C ******************************************************************* PROGRAM TCORR COMMON / BLOCK1 / STORX, STORY, STORZ COMMON / BLOCK2 / VX, VY, VZ COMMON / BLOCK3 / VACF, ANORM C ******************************************************************* C ** CALCULATION OF TIME CORRELATION FUNCTIONS. ** C ** ** C ** THIS PROGRAM ANALYZES DATA TO CALCULATE A TIME CORRELATION ** C ** FUNCTION IN ONE SWEEP (LOW MEMORY REQUIREMENT). IN THIS ** C ** EXAMPLE THE VELOCITY AUTO-CORRELATION FUNCTION IS CALCULATED. ** C ** ** C ** PRINCIPAL VARIABLES: ** C ** ** C ** INTEGER N NUMBER OF ATOMS ** C ** INTEGER NSTEP NUMBER OF STEPS ON THE TAPE ** C ** INTEGER IOR INTERVAL FOR TIME ORIGINS ** C ** INTEGER NT CORRELATION LENGTH, INCLUDING T=0 ** C ** INTEGER NTIMOR NUMBER OF TIME ORIGINS ** C ** INTEGER NLABEL LABEL FOR STEP (1,2,3...NSTEP) ** C ** REAL VX(N),VY(N),VZ(N) VELOCITIES ** C ** REAL VACF(NT) THE CORRELATION FUNCTION ** C ** NSTEP AND NT SHOULD BE MULTIPLES OF IOR. ** C ** ** C ** ROUTINES REFERENCED: ** C ** ** C ** SUBROUTINE STORE ( J1 ) ** C ** ROUTINE TO STORE THE DATA FOR CORRELATION ** C ** SUBROUTINE CORR ( J1, J2, IT ) ** C ** ROUTINE TO CORRELATE THE STORED TIME ORIGINS ** C ** ** C ** USAGE: ** C ** ** C ** DATA IN FILE DFILE ON FORTRAN UNIT DUNIT. ** C ** RESULTS IN FILE RFILE ON FORTRAN UNIT RUNIT. ** C ******************************************************************* INTEGER N, NSTEP, IOR, NT, NDIM, DUNIT, RUNIT, NTIMOR INTEGER FULLUP PARAMETER ( N = 256, NSTEP = 1000, IOR = 4, NT = 200 ) PARAMETER ( DUNIT = 10, RUNIT = 11 ) PARAMETER ( NDIM = NT / IOR + 1, NTIMOR = NSTEP / IOR ) PARAMETER ( FULLUP = NDIM - 1 ) REAL VX(N), VY(N), VZ(N) REAL STORX(NDIM,N), STORY(NDIM,N), STORZ(NDIM,N) REAL VACF(NT), ANORM(NT) INTEGER S(NTIMOR), TM(NTIMOR) INTEGER TS, TSS, L, NINCOR, K, JA, IB, IN, IA, JO, I INTEGER NLABEL CHARACTER DFILE * 30 CHARACTER RFILE * 30 C ******************************************************************* WRITE(*,'('' **** PROGRAM TCORR **** '')') WRITE(*,'('' CALCULATION OF TIME CORRELATION FUNCTIONS '')') C ** READ IN FILE NAMES ** WRITE(*,'('' ENTER DATA FILE NAME '')') READ (*,'(A)') DFILE WRITE (*,'('' ENTER RESULTS FILE NAME '')') READ (*,'(A)') RFILE C ** INITIALIZE COUNTERS ** NINCOR = FULLUP JA = 1 IA = 1 IB = 1 C ** ZERO ARRAYS ** DO 5 I = 1, NT VACF(I) = 0.0 ANORM(I) = 0.0 5 CONTINUE C ** OPEN DATA FILE AND RESULTS FILE ** OPEN ( UNIT = DUNIT, FILE = DFILE, ACCESS = 'SEQUENTIAL', : STATUS = 'OLD', FORM = 'UNFORMATTED' ) OPEN ( UNIT = RUNIT, FILE = RFILE, STATUS = 'NEW' ) C ** CALCULATION BEGINS ** DO 40 L = 1, NTIMOR JA = JA + 1 S(L) = JA - 1 READ ( DUNIT ) NLABEL, VX, VY, VZ TM(L) = NLABEL C ** STORE STEP AS A TIME ORIGIN ** CALL STORE ( JA ) C ** CORRELATE THE ORIGINS IN STORE ** DO 10 IN = IA, L TSS = TM(L) - TM(IN) TS = TSS + 1 JO = S(IN) + 1 CALL CORR ( JO, JA, TS ) 10 CONTINUE C ** READ IN DATA BETWEEN TIME ORIGINS. THIS CAN ** C ** BE CONVENIENTLY STORED IN ELEMENT 1 OF THE ** C ** ARRAYS STORX ETC. AND CAN THEN BE CORRELATED ** C ** WITH THE TIME ORIGINS. ** DO 30 K = 1, IOR - 1 READ ( DUNIT ) NLABEL, VX, VY, VZ CALL STORE ( 1 ) DO 20 IN = IA, L TSS = NLABEL - TM(IN) TS = TSS + 1 JO = S(IN) + 1 CALL CORR ( JO, 1, TS ) 20 CONTINUE 30 CONTINUE IF ( L .GE. FULLUP ) THEN IF ( L .EQ. NINCOR ) THEN NINCOR = NINCOR + FULLUP JA = 1 ENDIF IA = IA + 1 ENDIF 40 CONTINUE CLOSE ( UNIT = DUNIT ) C ** NORMALISE CORRELATION FUNCTIONS ** VACF(1) = VACF(1) / ANORM(1) / REAL ( N ) DO 50 I = 2, NT VACF(I) = VACF(I) / ANORM(I) / REAL ( N ) / VACF(1) 50 CONTINUE WRITE ( RUNIT, '('' VELOCITY ACF '')') WRITE ( RUNIT, '(I6,E15.6)') ( I, VACF(I), I = 1, NT ) CLOSE ( RUNIT ) STOP END SUBROUTINE STORE ( J1 ) COMMON/ BLOCK1 / STORX, STORY, STORZ COMMON/ BLOCK2 / VX, VY, VZ C ******************************************************************* C ** SUBROUTINE TO STORE TIME ORIGINS ** C ******************************************************************* INTEGER J1 INTEGER N, NT, IOR, NDIM PARAMETER ( N = 256, NT = 200, IOR = 4 ) PARAMETER ( NDIM = NT / IOR + 1 ) REAL STORX(NDIM,N), STORY(NDIM,N), STORZ(NDIM,N) REAL VX(N), VY(N), VZ(N) INTEGER I DO 10 I = 1, N STORX(J1,I) = VX(I) STORY(J1,I) = VY(I) STORZ(J1,I) = VZ(I) 10 CONTINUE RETURN END SUBROUTINE CORR ( J1, J2, IT ) COMMON/ BLOCK1 / STORX, STORY, STORZ COMMON/ BLOCK3 / VACF, ANORM C ******************************************************************* C ** SUBROUTINE TO CORRELATE TIME ORIGINS ** C ******************************************************************* INTEGER J1, J2, IT INTEGER N, NT, IOR, NDIM PARAMETER ( N = 256, NT = 200, IOR = 4 ) PARAMETER ( NDIM = NT / IOR + 1 ) REAL STORX(NDIM,N), STORY(NDIM,N), STORZ(NDIM,N) REAL VACF(NT), ANORM(NT) INTEGER I C ******************************************************************* DO 10 I = 1, N VACF(IT) = VACF(IT) + STORX(J1,I) * STORX(J2,I) : + STORY(J1,I) * STORY(J2,I) : + STORZ(J1,I) * STORZ(J2,I) 10 CONTINUE ANORM(IT) = ANORM(IT) + 1.0 RETURN END