C ******************************************************************* C ** FICHE F.16 ** C ** CONSTANT-NVT MONTE CARLO PROGRAM FOR HARD DUMB-BELLS. ** C ******************************************************************* PROGRAM MCBELL COMMON / BLOCK1 / RX, RY, RZ, EX, EY, EZ C ******************************************************************* C ** THE BOX IS OF UNIT LENGTH, -0.5 TO +0.5. THERE ARE NO LOOKUP ** C ** TABLES INCLUDED. ** C ** ** C ** PRINCIPAL VARIABLES: ** C ** ** C ** INTEGER N NUMBER OF MOLECULES ** C ** INTEGER NATOM NUMBER OF ATOMS PER MOLECULE ** C ** INTEGER NSTEP MAXIMUM NUMBER OF CYCLES ** C ** INTEGER IPRINT PRINT INTERVAL ** C ** INTEGR ISAVE SAVE INTERVAL ** C ** INTEGER IRATIO MAX DISPLACEMENT UPDATE INTERVAL ** C ** REAL RX(N),RY(N),RZ(N) POSITIONS ** C ** REAL EX(N),EY(N),EZ(N) ORIENTATIONS, UNIT AXIAL VECTOR ** C ** REAL DAB(NATOM) DISTANCE FROM COM TO NATOM ** C ** REAL D REDUCED BOND LENGTH (D/SIGMA) ** C ** REAL DENS REDUCED DENSITY ** C ** REAL SIGMA HARD SPHERE DIAMETER ** C ** REAL DRMAX REDUCED MAXIMUM DISPLACEMENT ** C ** REAL DOTMIN CONTROLS ANGULAR DISPLACEMENT ** C ** LOGICAL OVRLAP TRUE IF DUMBBELLS OVERLAP ** C ** ** C ** ROUTINES REFERENCED: ** C ** ** C ** SUBROUTINE CHECK ( SIGMA, DAB, OVRLAP ) ** C ** CHECKS FOR OVERLAPS IN A FLUID OF HARD DUMBELLS ** C ** SUBROUTINE ORIEN ( EXIOLD, EYIOLD, EZIOLD, DOTMIN, EXINEW, ** C ** : EYINEW, EZINEW ) ** C ** PRODUCES A TRIAL RANDOM ORIENTATION FOR A MOLECULE ** C ** REAL FUNCTION RANF( DUMMY ) ** C ** RETURNS A UNIFORM RANDOM NUMBER BETWEEN ZERO AND ONE ** C ** SUBROUTINE READCN ( CNFILE ) ** C ** READS IN A CONFIGURATION ** C ** SUBROUTINE TEST ( RXI, RYI, RZI, I, EXI, EYI, EZI, SIGMA, ** C ** : DAB, OVRLAP ) ** C ** CHECKS FOR OVERLAPS AFTER THE DISPLACEMENT OF MOLECULE I ** C ** SUBROUTINE WRITCN ( CNFILE ) ** C ** WRITES OUT A CONFIGURATION ** C ******************************************************************* INTEGER N, NATOM PARAMETER ( N = 108, NATOM = 2 ) REAL RX(N), RY(N), RZ(N), EX(N), EY(N), EZ(N) REAL DAB(NATOM), DRMAX, DOTMIN, DENS, D, SIGMA, RATIO REAL RXIOLD, RYIOLD, RZIOLD, RXINEW, RYINEW, RZINEW REAL EXIOLD, EYIOLD, EZIOLD, EXINEW, EYINEW, EZINEW REAL RANF, DUMMY, ACM, ACMMVA INTEGER STEP, I, NSTEP, IRATIO, IPRINT, ISAVE LOGICAL OVRLAP CHARACTER TITLE*80, CNFILE*80 C ******************************************************************* C ** READ INPUT DATA ** WRITE(*,'(1H1,'' **** PROGRAM MCBELL **** '')') WRITE(*,'(/ '' CONSTANT-NVT MONTE CARLO '')') WRITE(*,'( '' FOR HARD DUMBELLS ''/)') WRITE(*,'('' ENTER THE RUN TITLE '')') READ (*,'(A)') TITLE WRITE(*,'('' ENTER NUMBER OF CYCLES '')') READ (*,*) NSTEP WRITE(*,'('' ENTER NUMBER OF CYCLES BETWEEN OUTPUT '')') READ (*,*) IPRINT WRITE(*,'('' ENTER NUMBER OF CYCLES BETWEEN DATA SAVES '')') READ (*,*) ISAVE WRITE(*,'('' ENTER INTERVAL FOR UPDATE OF MAX. DISPL. '')') READ (*,*) IRATIO WRITE(*,'('' ENTER THE CONFIGURATION FILE NAME '')') READ (*,'(A)') CNFILE WRITE(*,'(/'' ENTER THE FOLLOWING IN LENNARD-JONES UNITS '',/)') WRITE(*,'('' ENTER THE DENSITY '')') READ (*,*) DENS WRITE(*,'('' ENTER THE MAXIMUM DISPLACEMENT '')') READ (*,*) DRMAX WRITE(*,'('' ENTER THE REDUCED BOND LENGTH '')') READ (*,*) D C ** WRITE INPUT DATA ** WRITE(*,'( //1X ,A )') TITLE WRITE(*,'('' NUMBER OF ATOMS '',I10 )') N WRITE(*,'('' NUMBER OF CYCLES '',I10 )') NSTEP WRITE(*,'('' OUTPUT FREQUENCY '',I10 )') IPRINT WRITE(*,'('' SAVE FREQUENCY '',I10 )') ISAVE WRITE(*,'('' RATIO UPDATE FREQUENCY '',I10 )') IRATIO WRITE(*,'('' CONFIGURATION FILE NAME '',A )') CNFILE WRITE(*,'('' DENSITY '',F10.5 )') DENS WRITE(*,'('' MAX. DISPLACEMENT '',F10.5 )') DRMAX WRITE(*,'('' BOND LENGTH '',F10.5 )') D C ** SET DEPENDENT VARIABLES ** SIGMA = ( DENS / REAL ( N ) ) ** ( 1.0 / 3.0 ) DAB(1) = D * SIGMA / 2.0 DAB(2) = - DAB(1) DRMAX = DRMAX * SIGMA DOTMIN = 0.2 C ** WRITE OUT SOME USEFUL INFORMATION ** WRITE( *, '( '' NUMBER OF MOLECULES = '', I10 )' ) N WRITE( *, '( '' NUMBER OF ATOMS = '', I10 )' ) NATOM WRITE( *, '( '' SIGMA / BOX = '', F10.5 )' ) SIGMA WRITE( *, '( '' DAB(1) / BOX = '', F10.5 )' ) DAB(1) WRITE( *, '( '' DAB(2) / BOX = '', F10.5 )' ) DAB(2) WRITE( *, '( '' DRMAX / BOX = '', F10.5 )' ) DRMAX WRITE( *, '( '' DOTMIN = '', F10.5 )' ) DOTMIN C ** READ IN INITIAL CONFIGURATION ** CALL READCN ( CNFILE ) C ** CHECK FOR OVERLAPS IN INITIAL CONFIGURATION ** CALL CHECK ( SIGMA, DAB, OVRLAP ) IF ( OVRLAP ) STOP 'OVERLAP IN INITIAL CONFIGURATION' C ** ZERO ACCUMULATORS ** ACM = 0.0 ACMMVA = 0.0 WRITE( *, '(//'' START OF MARKOV CHAIN ''//)') WRITE( *, '( '' ACM RATIO DRMAX DOTMIN '')') C ******************************************************************* C ** LOOP OVER CYCLES BEGINS ** C ******************************************************************* DO 100 STEP = 1, NSTEP C ** LOOP OVER MOLECULES ** DO 99 I = 1, N RXIOLD = RX(I) RYIOLD = RY(I) RZIOLD = RZ(I) EXIOLD = EX(I) EYIOLD = EY(I) EZIOLD = EZ(I) C ** MOVE I AND PICKUP THE CENTRAL IMAGE ** RXINEW = RXIOLD + ( 2.0 * RANF ( DUMMY ) - 1.0 ) * DRMAX RYINEW = RYIOLD + ( 2.0 * RANF ( DUMMY ) - 1.0 ) * DRMAX RZINEW = RZIOLD + ( 2.0 * RANF ( DUMMY ) - 1.0 ) * DRMAX RXINEW = RXINEW - ANINT ( RXINEW ) RYINEW = RYINEW - ANINT ( RYINEW ) RZINEW = RZINEW - ANINT ( RZINEW ) C ** CHANGE THE ORIENTATION OF MOLECULE I ** CALL ORIEN ( EXIOLD, EYIOLD, EZIOLD, DOTMIN, : EXINEW, EYINEW, EZINEW ) C ** CHECK FOR ACCEPTANCE ** CALL TEST ( RXINEW, RYINEW, RZINEW, I, : EXINEW, EYINEW, EZINEW, SIGMA, DAB, OVRLAP ) IF ( .NOT. OVRLAP ) THEN C ** ACCEPT MOVE ** RX(I) = RXINEW RY(I) = RYINEW RZ(I) = RZINEW EX(I) = EXINEW EY(I) = EYINEW EZ(I) = EZINEW ACMMVA = ACMMVA + 1.0 ENDIF ACM = ACM + 1.0 99 CONTINUE C **************************************************************** C ** LOOP OVER MOLECULES COMPLETE ** C **************************************************************** C ** PERFORM PERIODIC OPERATIONS ** C ** CHANGE MAXIMUM DISPLACEMENT ** IF ( MOD ( STEP, IRATIO ) .EQ. 0 ) THEN RATIO = ACMMVA / REAL ( N * IRATIO ) IF ( RATIO .GT. 0.5 ) THEN DRMAX = DRMAX * 1.05 DOTMIN = DOTMIN * 1.025 ELSE DRMAX = DRMAX * 0.95 DOTMIN = DOTMIN * 0.975 ENDIF ACMMVA = 0.0 ENDIF C ** WRITE OUT RUNTIME INFORMATION ** IF ( MOD ( STEP, IPRINT ) .EQ. 0 ) THEN WRITE(*,'(I8,3F10.4)') INT(ACM), RATIO, DRMAX, DOTMIN ENDIF C ** WRITE OUT THE CONFIGURATION AT INTERVALS ** IF ( MOD ( STEP, ISAVE ) .EQ. 0 ) THEN CALL WRITCN ( CNFILE ) CALL CHECK ( SIGMA, DAB, OVRLAP ) IF ( OVRLAP ) STOP 'OVERLAP DURING THE RUN' ENDIF 100 CONTINUE C ******************************************************************* C ** ENDS THE LOOP OVER CYCLES ** C ******************************************************************* C ** CHECKS FOR OVRLAPS IN THE FINAL CONFIGURATION ** CALL CHECK ( SIGMA, DAB, OVRLAP ) IF ( OVRLAP ) STOP 'OVERLAP IN FINAL CONFIGURATION' C ** WRITE OUT THE FINAL CONFIGURATION FROM THE RUN ** CALL WRITCN ( CNFILE ) STOP END SUBROUTINE ORIEN ( EXIOLD, EYIOLD, EZIOLD, DOTMIN, : EXINEW, EYINEW, EZINEW ) C ******************************************************************* C ** FINDS A TRIAL RANDOM ORIENTATION OF A LINEAR MOLECULE. ** C ** ** C ** PRINCIPAL VARIABLES: ** C ** ** C ** REAL EXIOLD,EYIOLD,EZIOLD OLD AXIAL VECTOR FOR I ** C ** REAL EYINEW,EYINEW,EZINEW NEW AXIAL VECTOR FOR I ** C ** REAL DOT DOT PRODUCT OF OLD AND NEW ** C ** AXIAL VECTORS ** C ** REAL DOTMIN MINIMUM ALLOWED DOT PRODUCT ** C ** ** C ** USAGE: ** C ** ** C ** THE METHOD USE A REJECTION TECHNIQUE TO CREATE A TRIAL ** C ** ORIENTATION OF MOLECULE I SUBJECT TO THE CONSTRAINT THAT ** C ** THE COSINE OF THE ANGLE BETWEEN THE OLD AND NEW AXIAL ** C ** VECTORS, DOT, IS GREATER THAN ( 1.0 - DOTMIN ). ** C ******************************************************************* REAL EXIOLD, EYIOLD, EZIOLD, EXINEW, EYINEW, EZINEW, DOTMIN REAL DOT, XI1, XI2, XI, XISQ REAL RANF, DUMMY C ******************************************************************* C ** INITIALISE DOT ** DOT = 0.0 C ** ITERATIVE LOOP ** 1000 IF ( ( 1.0 - DOT ) .GE. DOTMIN ) THEN C ** INITIALISE XISQ ** XISQ = 1.0 C ** INNER ITERATIVE LOOP ** 2000 IF ( XISQ .GE. 1.0 ) THEN XI1 = RANF ( DUMMY ) * 2.0 - 1.0 XI2 = RANF ( DUMMY ) * 2.0 - 1.0 XISQ = XI1 * XI1 + XI2 * XI2 GOTO 2000 ENDIF XI = SQRT ( 1.0 - XISQ ) EXINEW = 2.0 * XI1 * XI EYINEW = 2.0 * XI2 * XI EZINEW = 1.0 - 2.0 * XISQ DOT = EXINEW * EXIOLD + EYINEW * EYIOLD + EZINEW * EZIOLD GOTO 1000 ENDIF RETURN END SUBROUTINE TEST ( RXI, RYI, RZI, I, EXI, EYI, EZI, SIGMA, : DAB, OVRLAP ) COMMON / BLOCK1 / RX, RY,RZ, EX, EY, EZ C ******************************************************************* C ** CHECKS FOR OVERLAP OF I WITH ALL OTHER MOLECULES. ** C ** ** C ** PRINCIPAL VARIABLES: ** C ** ** C ** INTEGER I THE MOLECULE OF INTEREST ** C ** INTEGER N NUMBER OF MOLECULES ** C ** INTEGER NATOM NUMBER OF ATOMS PER MOLECULE ** C ** REAL RXI,RYI,RZI POSITION OF MOLECULE I ** C ** REAL EXI,EYI,EZI, ORIENTATION OF MOLECULE I ** C ** REAL RX(N),RY(N),RZ(N) MOLECULAR POSITIONS ** C ** REAL EX(N),EY(N),EZ(N) MOLECULAR ORIENTATIONS ** C ** REAL DAB(NATOM) POSITION OF ATOMS IN A MOLECULE ** C ** REAL SIGMA REDUCED ATOM DIAMETER ** C ** LOGICAL OVRLAP TRUE IF MOLECULE I OVERLAPS ** C ** ** C ** USAGE: ** C ** ** C ** CALLED AFTER A TRIAL DISPLACEMENT OF MOLECULE I TO ESTABLISH ** C ** WHETHER THERE IS AN OVERLAP IN THE TRIAL CONFIGURATION. ** C ******************************************************************* INTEGER NATOM, N PARAMETER ( NATOM = 2, N = 108 ) REAL RX(N), RY(N), RZ(N) REAL EX(N), EY(N), EZ(N) REAL RXI, RYI, RZI, EXI, EYI, EZI REAL SIGMA, DAB(NATOM) INTEGER I LOGICAL OVRLAP REAL RXIJ, RYIJ, RZIJ, EXJ, EYJ, EZJ REAL RXAB, RYAB, RZAB, DABI, SIGSQ, RABSQ INTEGER J, IA, JB C ******************************************************************* OVRLAP = .FALSE. SIGSQ = SIGMA * SIGMA C ** LOOPS OVER MOLECULES EXCEPT I ** DO 100 J = 1, N IF ( J .NE. I ) THEN EXJ = EX(J) EYJ = EY(J) EZJ = EZ(J) RXIJ = RXI - RX(J) RYIJ = RYI - RY(J) RZIJ = RZI - RZ(J) RXIJ = RXIJ - ANINT ( RXIJ ) RYIJ = RYIJ - ANINT ( RYIJ ) RZIJ = RZIJ - ANINT ( RZIJ ) C ** LOOPS OVER ATOMS ** DO 99 IA = 1, NATOM DABI = DAB(IA) DO 98 JB = 1, NATOM RXAB = RXIJ + EXI * DABI + EXJ * DAB(JB) RYAB = RYIJ + EYI * DABI + EYJ * DAB(JB) RZAB = RZIJ + EZI * DABI + EZJ * DAB(JB) RABSQ = RXAB * RXAB + RYAB * RYAB + RZAB * RZAB IF ( RABSQ .LT. SIGSQ ) THEN OVRLAP = .TRUE. RETURN ENDIF 98 CONTINUE 99 CONTINUE ENDIF 100 CONTINUE RETURN END SUBROUTINE CHECK ( SIGMA, DAB, OVRLAP ) COMMON / BLOCK1 / RX, RY, RZ, EX, EY, EZ C ******************************************************************* C ** ROUTINE TO CHECK FOR OVERLAPS IN A FLUID OF HARD DUMBBELLS ** C ** ** C ** PRINCIPAL VARIABLES: ** C ** ** C ** INTEGER N NUMBER OF MOLECULES ** C ** INTEGER NATOM NUMBER OF ATOMS PER MOLECULE ** C ** REAL RX(N),RY(N),RZ(N) MOLECULAR POSITIONS ** C ** REAL EX(N),EY(N),EZ(N) MOLECULAR ORIENTATIONS ** C ** REAL DAB(NATOM) POSITION OF ATOMS IN A MOLECULE ** C ** REAL SIGMA REDUCED ATOM DIAMETER ** C ** LOGICAL OVRLAP TRUE IF TWO DUMBELLS OVERLAP ** C ** ** C ** USAGE: ** C ** ** C ** CALLED AT INTERVALS DURING THE RUN TO CHECK FOR OVERLAPS. IF ** C ** OVRLAP IS RETURNED WITH A TRUE VALUE THEN THERE IS AN ERROR ** C ** IN THE PROGRAM AND THE EXECUTION IS STOPPED. ** C ******************************************************************* INTEGER NATOM, N PARAMETER ( NATOM = 2, N = 108 ) REAL RX(N), RY(N), RZ(N) REAL EX(N), EY(N), EZ(N) REAL SIGMA, DAB(NATOM) LOGICAL OVRLAP REAL RXI, RYI, RZI, RXIJ, RYIJ, RZIJ, EXI, EYI, EZI REAL EXJ, EYJ, EZJ, RXAB, RYAB, RZAB, DABI, SIGSQ, RABSQ INTEGER I, J, IA, JB C ******************************************************************* OVRLAP = .FALSE. SIGSQ = SIGMA * SIGMA C ** LOOPS OVER MOLECULES ** DO 100 I = 1, N - 1 RXI = RX(I) RYI = RY(I) RZI = RZ(I) EXI = EX(I) EYI = EY(I) EZI = EZ(I) DO 99 J = I + 1, N RXIJ = RXI - RX(J) RYIJ = RYI - RY(J) RZIJ = RZI - RZ(J) RXIJ = RXIJ - ANINT ( RXIJ ) RYIJ = RYIJ - ANINT ( RYIJ ) RZIJ = RZIJ - ANINT ( RZIJ ) EXJ = EX(J) EYJ = EY(J) EZJ = EZ(J) C ** LOOPS OVER ATOMS ** DO 98 IA = 1, NATOM DABI = DAB(IA) DO 97 JB = 1, NATOM RXAB = RXIJ + EXI * DABI + EXJ * DAB(JB) RYAB = RYIJ + EYI * DABI + EYJ * DAB(JB) RZAB = RZIJ + EZI * DABI + EZJ * DAB(JB) RABSQ = RXAB * RXAB + RYAB * RYAB + RZAB * RZAB IF ( RABSQ .LT. SIGSQ ) THEN OVRLAP = .TRUE. RETURN ENDIF 97 CONTINUE 98 CONTINUE 99 CONTINUE 100 CONTINUE RETURN END SUBROUTINE READCN ( CNFILE ) COMMON / BLOCK1 / RX, RY, RZ, EX, EY, EZ C ******************************************************************* C ** SUBROUTINE TO READ IN THE CONFIGURATION FROM UNIT 10 ** C ******************************************************************* INTEGER N PARAMETER ( N = 108 ) CHARACTER CNFILE*(*) REAL RX(N), RY(N), RZ(N), EX(N), EY(N), EZ(N) INTEGER CNUNIT PARAMETER ( CNUNIT = 10 ) INTEGER NN C ******************************************************************** OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'OLD', : FORM = 'UNFORMATTED' ) READ ( CNUNIT ) NN IF ( NN .NE. N ) STOP 'N ERROR IN READCN' READ ( CNUNIT ) RX, RY, RZ READ ( CNUNIT ) EX, EY, EZ CLOSE ( UNIT = CNUNIT ) RETURN END SUBROUTINE WRITCN ( CNFILE ) COMMON / BLOCK1 / RX, RY, RZ, EX, EY, EZ C ******************************************************************* C ** SUBROUTINE TO WRITE OUT THE CONFIGURATION TO UNIT 10 ** C ******************************************************************* INTEGER N PARAMETER ( N = 108 ) CHARACTER CNFILE*(*) REAL RX(N), RY(N), RZ(N), EX(N), EY(N), EZ(N) INTEGER CNUNIT PARAMETER ( CNUNIT = 10 ) C ******************************************************************** OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'UNKNOWN', : FORM = 'UNFORMATTED' ) WRITE ( CNUNIT ) N WRITE ( CNUNIT ) RX, RY, RZ WRITE ( CNUNIT ) EX, EY, EZ CLOSE ( UNIT = CNUNIT ) RETURN END REAL FUNCTION RANF ( DUMMY ) C ******************************************************************* C ** RETURNS A UNIFORM RANDOM VARIATE IN THE RANGE 0 TO 1. ** C ** ** C ** *************** ** C ** ** WARNING ** ** C ** *************** ** C ** ** C ** GOOD RANDOM NUMBER GENERATORS ARE MACHINE SPECIFIC. ** C ** PLEASE USE THE ONE RECOMMENDED FOR YOUR MACHINE. ** C ******************************************************************* INTEGER L, C, M PARAMETER ( L = 1029, C = 221591, M = 1048576 ) INTEGER SEED REAL DUMMY SAVE SEED DATA SEED / 0 / C ******************************************************************* SEED = MOD ( SEED * L + C, M ) RANF = REAL ( SEED ) / M RETURN END