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PREFACTOR

Specifies coefficients for defining prefactors in mineral precipitation-dissolution reactions.

\[{{{\mathcal P}}}_{ml} = \prod_i\dfrac{\big(\gamma_i m_i\big)^{{{\alpha}}_{il}^m}}{1+K_{il}^m\big(\gamma_i m_i\big)^{{{\beta}}_{il}^m} }\]

Required Cards:

PREFACTOR_SPECIES <string>

Name of prefactor species. Appears as subscripts j and i in above equation corresponding to primary and secondary species.

RATE_CONSTANT <float> <optional units_string>

Kinetic rate constant associated with prefactor species (see MINERAL_KINETICS). (default units [mol/m²/sec])

Optional Cards:

ACTIVATION_ENERGY <float>

Activation energy associated with rate constant \(k_{ml}\). [J/mol]

ALPHA <float>

\(\alpha_{il}^m\) parameter in above equation.

BETA <float>

\(\beta_{il}^m\) parameter in above equation.

ATTENUATION_COEF <float>

\(K_{il}^m\) in above equation.

Examples (data from Palandri and Kharaka (2004))

CHEMISTRY
  ...
  MINERAL_KINETICS
    K-Feldspar
      PREFACTOR
        RATE_CONSTANT -12.41d0 mol/m^2-sec
        ACTIVATION_ENERGY 38.d0
      /
      PREFACTOR
        RATE_CONSTANT -10.06d0 mol/m^2-sec
        ACTIVATION_ENERGY 51.7d0
        PREFACTOR_SPECIES H+
          ALPHA 0.5d0
        /
      /
      PREFACTOR
        RATE_CONSTANT -21.20 mol/m^2-sec
        ACTIVATION_ENERGY 94.1d0
        PREFACTOR_SPECIES H+
          ALPHA -0.823d0
        /
      /
    /
  /
  ...
END