CKFALP    CKFALP    CKFALP    CKFALP    CKFALP    CKFALP    CKFALP    
          **********************************************
                    **************************
                              ******

SUBROUTINE CKFALP (P, T, X, ICKWRK, RCKWRK, I, RKLOW, CTB, PR, FC,
                   PCOR)
Returns details concerning the reaction rate constant for
pressure-dependent reactions.

INPUT
P      - Pressure.
              cgs units - dynes/cm**2
              Data type - real scalar
T(*)   - Temperature array.
              cgs units - K
              Data type - real vector
X      - Mole fractions of the species.
              cgs units - none
              Data type - real array
              Dimension X(*) at least KK, the total number of
              species.
ICKWRK - Array of integer workspace.
              Data type - integer array
              Dimension ICKWRK(*) at least LENIWK.
RCKWRK - Array of real work space.
              Data type - real array
              Dimension RCKWRK(*) at least LENRWK.

OUTPUT
RKLOW    - Low Pressure forward reaction rate for pressure-
           dependent reactions. It is defined to be zero for
           non-pressure-dependent reactions.
              cgs units - 1/(sec) *
                      (cm**3/mole)**(sum of forward stoich. coeff)
              Data type - real
CTB      - Effective concentration for reaction, I_SAVE.
           This takes into account the effectiveness factors
           for the reaction, applicable to third body
           and pressure-dependent reactions.  It is defined to be
           equal to the total concentration for other pressure-
           dependent or third body reactions, and to be equal to
           one for reactions which don't use it
           Units are moles/cm**3.
              cgs units - mole/(cm**3)
              Data type - real
PR       - Reduced Pressure for pressure-dependent reactions.
           This is defined to be equal to CTB*RKLOW_SAVE/RCF_INF.
           where RCF_INF is the high pressure rate constant.
           This is a dimensionless quantity.  For non-pressure-
           dependent reactions, this quantity is defined to be 0.
              cgs units - unitless
              Data type - real
FC       - Correction to L-H rate constant for pressure-dependent
           reactions.  It is defined to be 0 for non-pressure-
           dependent reactions.
              cgs units - unitless
              Data type - real
PCOR     - This is equal to the pressure correction ratio for
           pressure-dependent reactions, that is, RC(T,P) / RC(T)_inf
           the ratio of the actual reaction rate to the high
           pressure reaction rate constant.
              cgs units - unitless
              Data type - real array