C SUBROUTINE PREPOT C C System: OH2 C Functional form: LEPS (London-Eyring-Polanyi-Sato) plus a correction term C Common name: JWS C References: G. C. Schatz C J. Chem. Phys. 83, 5677 (1985) C B. R. Johnson and N. W. Winter C J. Chem. Phys. 66, 4116 (1977). C C Calling Sequence: C PREPOT - initializes the potential's variables and C must be called once before any calls to POT C POT - driver for the evaluation of the energy and the derivatives C of the energy with respect to the coordinates for a given C geometric configuration C C Units: C energies - hartrees C coordinates - bohrs C derivatives - hartrees/bohr C C Surfaces: C ground electronic state C C Zero of energy: C The classical potential energy is set equal to zero for the O C infinitely far from the H2 diatomic and R(H2) set equal to the C H2 equilibrium diatomic value. C C Parameters: C Set in the BLOCK DATA subprogram PTPACM C C Coordinates: C Internal, Definition: R(1) = R(O-first H) C R(2) = R(first H-second H) C R(3) = R(second H-O) C C Common Blocks (used between the calling program and this potential): C passes the coordinates, energy, and derivatives of C the energy with respect to the coordinates. C passes the control flags where C NDER = 0 => no derivatives are calculated C NDER = 1 => calculate first derivatives of the energy for the C ground electronic state with respect to the coordinates C NFLAG Control flags C NFLAG(18-20) C passes the FORTRAN unit number used for potential output C /ASYCM/ EASYAB, EASYBC, EASYAC C passes the energy in the three asymptotic valleys for an A+BC system. C The energy in the AB valley, EASYAB, is equal to the energy C of the C atom "infinitely" far from the AB diatomic and R(AB) set C equal to Re(AB), the equilibrium bond length for the AB diatomic. C In this potential the AB valley represents H infinitely far from C the OH diatomic and R(OH) equal to Re(OH). C Similarly, the terms EASYBC and EASYAC represent the energies in the C H2 and the other OH asymptotic valleys, respectively. C C Default Parameter Values: C Variable Default value C NDER 1 C NFLAG(18) 6 C C***** C IMPLICIT DOUBLE PRECISION (A-H,O-Z) C CHARACTER*75 REF(5) C PARAMETER (N3ATOM = 75) PARAMETER (ISURF = 5) PARAMETER (JSURF = ISURF*(ISURF+1)/2) PARAMETER (PI = 3.141592653589793D0) PARAMETER (NATOM = 25) C COMMON /PT3CM/ EZERO(ISURF+1) C COMMON/INFOCM/ CARTNU(NATOM,3),INDEXES(NATOM), + IRCTNT,NATOMS,ICARTR,MDER,MSURF,REF C C COMMON/USRICM/ CART(NATOM,3),ANUZERO, + NULBL(NATOM),NFLAG(20), + NASURF(ISURF+1,ISURF+1),NDER C COMMON /ASYCM/ EASYAB,EASYBC,EASYAC C PARAMETER (R2 = 1.41421356D0) PARAMETER (CKCAU = 627.5095D0) PARAMETER (CANGAU = 0.52917706D0) C COMMON /SATOCM/ D(3),RE(3),BETA(3),Z(3) C COMMON /PRECM/ ZPO(3),OP3Z(3),ZP3(3),TZP3(3),TOP3Z(3), + DO4Z(3),B(3),X(3),COUL(3),EXCH(3) C C Echo the potential parameters to the file linked to UNIT NFLAG(18) C IF(NATOMS.GT.25) THEN WRITE(NFLAG(18),1111) 1111 FORMAT(2X,'STOP. NUMBER OF ATOMS EXCEEDS ARRAY DIMENSIONS') STOP END IF C WRITE (NFLAG(18), 600) D, RE, BETA, Z C 600 FORMAT(/,1X,'*****',1X,'Potential Energy Surface',1X,'*****',/, * /,1X,T5,'OH2 JWS potential energy surface', * //,1X,T5,'Parameters:', * /,1X,T5,'Bond', T47, 'O-H', T58, 'H-H', T69, 'H-O', * /,1X,T5,'Dissociation energies (kcal/mol):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Equilibrium bond lengths (Angstroms):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Morse beta parameters (Angstroms**-1):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Sato parameters:', * T44, F10.5, T55, F10.5, T66, F10.5,//,1X,'*****') C C CONVERT TO ATOMIC UNITS C DO 10 I = 1,3 D(I)=D(I)/CKCAU RE(I) = RE(I)/CANGAU BETA(I) = BETA(I)*CANGAU C C COMPUTE USEFUL CONSTANTS C ZPO(I) = 1.0D0 + Z(I) OP3Z(I) = 1.0D0 + 3.0D0*Z(I) TOP3Z(I) = 2.0D0*OP3Z(I) ZP3(I) = Z(I) + 3.0D0 TZP3(I) = 2.0D0*ZP3(I) DO4Z(I) = D(I)/4.0D0/ZPO(I) B(I) = BETA(I)*DO4Z(I)*2.0D0 10 CONTINUE C C Initialize the asymptotic energy values C EASYAB = D(1) EASYBC = D(2) EASYAC = D(3) C C EZERO(1)=D(2) C DO I=1,5 REF(I) = ' ' END DO C REF(1)='B. R. Johnson, N. W. Winter' REF(2)='J. Chem. Phys. 66, 4116(1977)' REF(3)='G. C. Schatz' REF(4)='J. Chem. Phys. 83, 5677(1985)' C INDEXES(1) = 8 INDEXES(2) = 1 INDEXES(3) = 1 C C C IRCTNT=2 C CALL POTINFO C CALL ANCVRT C RETURN END C SUBROUTINE POT C C C Surfaces: C ground electronic state C C Zero of energy: C The classical potential energy is set equal to zero for the O C infinitely far from the H2 diatomic and R(H2) set equal to the C H2 equilibrium diatomic value. C C Coordinates: C Internal, Definition: R(1) = R(O-first H) C R(2) = R(first H-second H) C R(3) = R(second H-O) C C ENTRY POT IMPLICIT DOUBLE PRECISION (A-H,O-Z) C CHARACTER*75 REF(5) C PARAMETER (N3ATOM = 75) PARAMETER (ISURF = 5) PARAMETER (JSURF = ISURF*(ISURF+1)/2) PARAMETER (PI = 3.141592653589793D0) PARAMETER (NATOM = 25) C COMMON /PT1CM/ R(N3ATOM),ENGYGS,DEGSDR(N3ATOM) COMMON /PT3CM/ EZERO(ISURF+1) COMMON /PT4CM/ ENGYES(ISURF),DEESDR(N3ATOM,ISURF) COMMON /PT5CM/ ENGYIJ(JSURF),DEIJDR(N3ATOM,JSURF) C COMMON/INFOCM/ CARTNU(NATOM,3),INDEXES(NATOM), + IRCTNT,NATOMS,ICARTR,MDER,MSURF,REF C COMMON/USROCM/ PENGYGS,PENGYES(ISURF), + PENGYIJ(JSURF), + DGSCART(NATOM,3),DESCART(NATOM,3,ISURF), + DIJCART(NATOM,3,JSURF) C COMMON/USRICM/ CART(NATOM,3),ANUZERO, + NULBL(NATOM),NFLAG(20), + NASURF(ISURF+1,ISURF+1),NDER C COMMON /ASYCM/ EASYAB,EASYBC,EASYAC C PARAMETER (R2 = 1.41421356D0) PARAMETER (CKCAU = 627.5095D0) PARAMETER (CANGAU = 0.52917706D0) C COMMON /SATOCM/ D(3),RE(3),BETA(3),Z(3) C COMMON /PRECM/ ZPO(3),OP3Z(3),ZP3(3),TZP3(3),TOP3Z(3), + DO4Z(3),B(3),X(3),COUL(3),EXCH(3) C CALL CARTOU CALL CARTTOR C C Check the value of NDER C IF (NDER .GT. 1) THEN WRITE (NFLAG(18), 900) NDER STOP 'POT 1' ENDIF C C Compute the LEPS potential - this is equivalent to the JW OH2 potential. C DO 21 I = 1,3 X(I) = EXP(-BETA(I)*(R(I)-RE(I))) COUL(I) = DO4Z(I)*(ZP3(I)*X(I)-TOP3Z(I))*X(I) EXCH(I) = DO4Z(I)*(OP3Z(I)*X(I)-TZP3(I))*X(I) 21 CONTINUE RAD = SQRT((EXCH(1)-EXCH(2))**2 + (EXCH(2)-EXCH(3))**2 + + (EXCH(3)-EXCH(1))**2) ENGYGS = COUL(1) + COUL(2) + COUL(3) - (RAD/R2) + + EZERO(1) - ANUZERO C C Compute the derivatives of the LEPS energy w.r.t.the coordinates C IF (NDER .EQ. 1) THEN SVAL = EXCH(1) + EXCH(2) + EXCH(3) DO 22 I = 1,3 DEGSDR(I)=0.0D0 IF(X(I).LT.1.0D-30) GO TO 22 TVAL = (3.0D0*EXCH(I)-SVAL)/R2*(OP3Z(I)*X(I)-ZP3(I)) IF(ABS(RAD) .LT. 1.0D-32 .AND. + ABS(TVAL) .GT. 1.0D-12) THEN WRITE(NFLAG(18), 6000) TVAL, RAD ELSE IF(ABS(RAD).GT.1.0D-32) THEN TVAL = TVAL/RAD END IF DEGSDR(I)=B(I)*X(I)*(TVAL-ZP3(I)*X(I)+OP3Z(I)) 22 CONTINUE ENDIF C C George Schatz's correction term to JW LEPS surface C T1 = R(1) - 2.105D0 T2 = R(3) - 2.105D0 T3 = R(2) - 4.21D0 VCOR = 0.04382D0*EXP(-T1*T1 - T2*T2 - 0.5D0*T3*T3) ENGYGS = ENGYGS + VCOR IF (NDER .EQ. 1) THEN DEGSDR(1) = DEGSDR(1) - 2.D0*T1*VCOR DEGSDR(3) = DEGSDR(3) - 2.D0*T2*VCOR DEGSDR(2) = DEGSDR(2) - T3*VCOR ENDIF C 600 FORMAT(/,1X,'*****',1X,'Potential Energy Surface',1X,'*****',/, * /,1X,T5,'OH2 JWS potential energy surface', * //,1X,T5,'Parameters:', * /,1X,T5,'Bond', T47, 'O-H', T58, 'H-H', T69, 'H-O', * /,1X,T5,'Dissociation energies (kcal/mol):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Equilibrium bond lengths (Angstroms):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Morse beta parameters (Angstroms**-1):', * T44, F10.5, T55, F10.5, T66, F10.5, * /,1X,T5,'Sato parameters:', * T44, F10.5, T55, F10.5, T66, F10.5,//,1X,'*****') 900 FORMAT(/,1X,T5,'Error: POT has been called with NDER = ', I5, * /,1X,T12,'only the first derivatives, NDER = 1, are ', * 'coded in this potential') 6000 FORMAT(/,2X,'In the OH2 potential JWS, T, RAD = ',1P,2E15.7, 1 /,2X,'T/RAD has been set equal to T') C CALL EUNITZERO IF(NDER.NE.0) THEN CALL RTOCART CALL DEDCOU ENDIF C RETURN END C C***** C BLOCK DATA PTPACM IMPLICIT DOUBLE PRECISION (A-H,O-Z) C CHARACTER*75 REF(5) C PARAMETER (N3ATOM = 75) PARAMETER (ISURF = 5) PARAMETER (JSURF = ISURF*(ISURF+1)/2) PARAMETER (PI = 3.141592653589793D0) PARAMETER (NATOM = 25) C COMMON /PT3CM/ EZERO(ISURF+1) C COMMON/INFOCM/ CARTNU(NATOM,3),INDEXES(NATOM), + IRCTNT,NATOMS,ICARTR,MDER,MSURF,REF C C COMMON/USRICM/ CART(NATOM,3),ANUZERO, + NULBL(NATOM),NFLAG(20), + NASURF(ISURF+1,ISURF+1),NDER C COMMON /ASYCM/ EASYAB,EASYBC,EASYAC C COMMON /SATOCM/ D(3), RE(3), BETA(3), Z(3) C C Initialize the flags and the I/O unit numbers for the potential C DATA NASURF /1,35*0/ DATA NDER /0/ DATA NFLAG /1,1,15*0,6,0,0/ C DATA ANUZERO /0.0D0/ DATA ICARTR,MSURF,MDER/3,0,1/ DATA NULBL /25*0/ DATA NATOMS /3/ C C Initialize the potential parameters; the energy parameters C are in kcal/mol, and the lengths are in Angstroms. C DATA D / 106.6D0, 109.4D0, 106.6D0/ DATA RE / 0.9706D0, 0.7417D0, 0.9706D0/ DATA BETA / 2.294D0, 1.942D0, 2.294D0/ DATA Z / 0.0885D0, 0.0885D0, 0.0885D0/ C END C C*****