C SUBROUTINE prepot C C System: ClHBr C Functional form: Extended LEPS (London-Erying-Polyani-Sato) C C References for the potential parameters and the potential functional form: C Morse Parameters: D. J. Douglas, J. C. Polanyi, and J. J. Sloan C Chem. Phys. 13, 15 (1976). C Sato Parameters: V. K. Babamov, V. Lopez, and R. A. Marcus C J. Chem. Phys. 78, 5621 (1983). C Functional form: P. J. Kuntz, E. M. Nemth, J. C. Polanyi, S. D. Rosner, C and C. E. Young C J. Chem. Phys. 44, 1168 (1966) C C PREPOT must be called once before any calls to POT. C The potential parameters are included in DATA statements. C Coordinates, potential energy, and derivatives are passed C through the common block POTCM: C COMMON /POTCM/ R(3), ENERGY, DEDR(3) C The potential parameters are passed through the common blocks C SATOCM and LEPSCM. C All the information passed through the common blocks POTCM, SATOCM, C and LEPSCM are in hartree atomic units. C C This potential is written such that: C R(1) = R(Cl-H) C R(2) = R(H-Br) C R(3) = R(Br-Cl) C C The the flags that indicate what calculations should be carried out in C the potential routine are passed through the common block POTCCM: C /POTCCM/ NSURF, NDER, NDUM(8) C where: C NSURF - which electronic state should be used. C This option is not used for this potential as only the C ground electronic state is available. C NDER = 0 => no derivatives should be calculated C NDER = 1 => calculate first derivatives C NDUM - these 8 integer values can be used to flag options C within the potential; in this potential these options C are not used. C IMPLICIT DOUBLE PRECISION (A-H,O-Z) COMMON /POTCM/ R(3), ENERGY, DEDR(3) COMMON /POTCCM/ NSURF, NDER, NDUM(8) COMMON /SATOCM/ D(3), RE(3), BETA(3), Z(3) COMMON /LEPSCM/ ZPO(3), OP3Z(3), ZP3(3), TZP3(3), TOP3Z(3), * DO4Z(3), B(3) PARAMETER (CKCAL = 627.5095D0) PARAMETER (CANGS = 0.529177106D0) DIMENSION DEI(3), REI(3), BETAI(3), ZI(3) C C Data statements for the potential parameters; the energy parameters are in C kcal/mol, and the lengths are in Angstroms. C DATA DEI/ 106.4D0, 90.24D0, 52.09D0/ DATA REI/ 1.275D0, 1.414D0, 2.136D0/ DATA BETAI/1.867D0, 1.851D0, 1.923D0/ DATA ZI/0.02D0, 0.02D0, 0.0D0/ C C Set the flags for the type of calculations to be carried out by the C potential. C NDER = 1 WRITE (6, 100) DEI, REI, BETAI, ZI C 100 FORMAT (/, 2X, T5, 'PREPOT has been called for Cl + HBr', * /, 2X, T5, 'Extended LEPS function', * //, 2X, T5, 'Potential energy surface parameters:', * /, 2X, T5, 'Bond', T47, 'Cl-H', T58, 'H-Br', T69, 'Br-Cl', * /, 2X, T5, 'Dissociation energies (kcal/mol):', * T44, F10.5, T55, F10.5, T66, F10.5, * /, 2X, T5, 'Equilibrium bond lengths (Angstroms):', * T44, F10.5, T55, F10.5, T66, F10.5, * /, 2X, T5, 'Morse beta parameters (Angstroms**-1):', * T44, F10.5, T55, F10.5, T66, F10.5, * /, 2X, T5, 'Sato parameters:', * T44, F10.5, T55, F10.5, T66, F10.5,/) C DO 10 I = 1,3 Z(I) = ZI(I) C Convert to atomic units D(I) = DEI(I)/CKCAL RE(I) = REI(I)/CANGS BETA(I) = BETAI(I)*CANGS C Compute useful constants 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 RETURN END C***** C SUBROUTINE pot C C System: ABC C Functional form: Extended LEPS (London-Erying-Polyani-Sato) C References: P. J. Kuntz, E. M. Nemth, J. C. Polanyi, S. D. Rosner, C and C. E. Young C J. Chem. Phys. 44, 1168 (1966) C C PREPOT must be called once before any calls to POT. C The potential parameters are initialized in the subprogram PREPOT. C Coordinates, potential energy, and derivatives are passed C through the common block POTCM: C COMMON /POTCM/ R(3), ENERGY, DEDR(3) C The constants for the potential are passed through the common blocks C SATOCM and LEPSCM. C All the information passed through the common blocks POTCM, SATOCM, C and LEPSCM are in hartree atomic units. C C For the reaction: A + BC -> AB + C we write: C R(1) = R(A-B) C R(2) = R(B-C) C R(3) = R(C-A) C C NOTE: The potential energy at the reactant asympotote is not equal to C zero, it is set equal to the energy of the reactant diatomic. C C The the flags that indicate what calculations should be carried out in C the potential routine are passed through the common block POTCCM: C /POTCCM/ NSURF, NDER, NDUM(8) C where: C NSURF - which electronic surface should be used. C In this potential this option is not used; the ground C electronic state is the only one available. C NDER = 0 => no derivatives should be calculated C NDER = 1 => calculate first derivatives C NDUM - these 8 integer values can be used to flag options C within the potential; in this potential these options C are not used. C IMPLICIT DOUBLE PRECISION (A-H,O-Z) COMMON /POTCM/R(3), ENERGY, DEDR(3) COMMON /POTCCM/ NSURF, NDER, NDUM(8) COMMON /SATOCM/ D(3), RE(3), BETA(3), Z(3) COMMON /LEPSCM/ ZPO(3), OP3Z(3), ZP3(3), TZP3(3), TOP3Z(3), * DO4Z(3), B(3) DIMENSION X(3), COUL(3), EXCH(3) PARAMETER (R2 = 1.41421356D0) C C Initialize the variable used in the calculation of the energy. C ENERGY = 0.D0 C C Compute the energy. C DO 10 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) ENERGY = ENERGY + COUL(I) 10 CONTINUE C RAD = SQRT((EXCH(1)-EXCH(2))**2 + (EXCH(2)-EXCH(3))**2 + * (EXCH(3)-EXCH(1))**2) C ENERGY = ENERGY - RAD/R2 C C Compute the derivatives of the energy with respect to the internal C coordinates. C IF (NDER .EQ. 1) THEN S = EXCH(1) + EXCH(2) + EXCH(3) DO 20 I = 1,3 DEDR(I) = B(I)*X(I)*((3.0D0*EXCH(I)-S)/R2* * (OP3Z(I)*X(I)-ZP3(I))/RAD- * ZP3(I)*X(I)+OP3Z(I)) 20 CONTINUE ENDIF C RETURN END C*****