4.5.3. Auxiliary Reaction Data

Auxiliary information appears on one or more separate lines after the reaction data line is read, and serves to modify or give additional parameters needed to evaluate that reaction's rate expression. The format in an auxiliary information line is a character string keyword followed by a slash-delimited (/) field containing an appropriate number of parameters (either integer, floating point, E format, or character). Examples of many of the auxiliary options described in this section are shown in Figure 4.7: Examples of Auxiliary Reaction Data . Table 4.6: Alphabetical Listing of Surface Reaction Auxiliary Keywords provides detailed information on the meaning and usage of each auxiliary keyword entry that may be included as part of the Surface Reaction Data.

Auxiliary reactions for multiphase chemistry follow the similar format as specified above. Liquid-phase–specific data are described in Table 4.7: Auxiliary Keywords for Liquid Phase Reactions. An example of the use of these data in a multiphase kinetics input file is show in Figure 4.8: Examples of Auxiliary Reaction Data for Liquid Phase.

Table 4.6: Alphabetical Listing of Surface Reaction Auxiliary Keywords

Keyword	Definition
BOHM	Bohm Velocity Limit for Ions - Applies the Bohm velocity correction for a reaction involving a positive ionic species (see Equation 4–29 of the Chemkin Theory Manual ). No auxiliary parameters are required.
	Reaction Example	`CL+ + E => CL 0.4 0.0 0.0` `BOHM`
	Notes	The three coefficients given in the second field of the reaction line are interpreted as the parameters , , , in Equation 4–29 of the Chemkin Theory Manual ). The reaction can have only one gas-phase reactant species, which must be a positive ion, and its stoichiometric coefficient must be 1.
COV	Coverage Dependent Reactions - Modifies the expression for the forward rate constant by coverage parameters (see Equation 4–7 of the Chemkin Theory Manual ). Must be followed by (slash delimited) surface species name and the three parameters , and .
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	COV /Pt(S) 0.0 0.0 0.9/
	Coverage parameter	Required	--	COV /Pt(S) 0.0 0.0 0.9/
	Coverage parameter	Required	--	COV /Pt(S) 0.0 0.0 0.9/
	Coverage parameter	Required	cal/mole	COV /Pt(S) 0.0 0.0 0.9 /
	Reaction Example	`O(S) +O(S) =>Pt(S) +Pt(S) +O2 3.700E+23 0.0 213.0` `COV/O(S) 0.0 0.0 -93.3/`
	Notes	More than one set of `COV` data can appear for a given reaction, and these would be applied multiplicatively as in Equation 4–7 of the Chemkin Theory Manual .
DCOL	The reaction rate is proportional to the collision frequency between a gas molecule and a particle surface (see Equation 19–79 of the Chemkin Theory Manual ). Must be followed by the (slash delimited) collision-diameter of the gas-phase reactant.
	Parameters	Optional/Reqd.	Units	Examples
	Collision diameter	Required	cm	DCOL /2.45E-8/
	Reaction Example	`A1 + 8H(se) => 5H(se) + 6C(B) + 3open(se) + 4H2 + H 0.1 0.0 0.0` `FORD/H(se) 2.0/` `DCOL/2.46E-8/` `STICK`
	Notes	The reaction must be irreversible. The reaction may have only one gas-phase.
DUP	Duplicate Reactions - Two or more reactions can involve the same set of reactants and products, but proceed through distinctly different processes. In these cases, it may be appropriate to state a reaction mechanism that has two or more reactions that are the same, but have different rate parameters. However, duplicate reactions are normally considered errors by the Surface Kinetics Pre-Processor. If the user requires duplication (for example, the same reactants and products with different Arrhenius parameters), keyword `DUP` must follow the reaction line of each duplicate reaction (including the first occurrence of the reaction that is duplicated). For example, if the user wishes to specify different rate expressions for each of two identical reactions, there must be two occurrences of the `DUP` keyword, one following each of the reactions. No auxiliary parameters are required.
	Reaction Example	`O2 + 2PT(S) => 2O(S) 1.80E+21 -0.5 0.0` `DUP` `O2 + 2PT(S) => 2O(S) 0.023 0.00 0.00` `DUP`
	Notes	`DUP` is required for each of any duplicated reaction in the mechanism.
ENRGDEP	Ion-energy Dependent Rates - Allows the rate constant to depend on ion energy according to Equation 4–30 of the Chemkin Theory Manual . `ENRGDEP` must be followed by the three (slash delimited) E _{ion, 0}, , and .
	Parameters	Optional/Reqd.	Units	Examples
	Threshold energy E _{ion, 0}	Required	cal/mole	ENRGDEP /1.0 0.5 1.0/
	Exponential constant f _i	Required	--	ENRGDEP /1.0 0.5 1.0/
	Exponential constant g _i	Required	--	ENRGDEP /1.0 0.5 1.0/
	Reaction Example	`E + CL+ + SICL3(S) + SI(B) => SICL4 + SI(S) 0.50 0.0 0.` `BOHM` `ENRGDEP/1. 0.5 1.0/ UNITS/EVOLT/`
	Notes	There must be exactly one positive ionic reactant species in the reaction. Only irreversible reactions are allowed with this option.
FORD	Arbitrary Reaction Orders - Supersedes the forward reaction order for any species in the mechanism (with respect to species concentration), regardless of whether the species appears as a reactant or a product in the reaction. `FORD` is followed, in slash-delimited format, by the species name and the new reaction order. This option overrides the values of in Equation 3–4 of the Chemkin Theory Manual pertaining to the particular species named on the line; the reaction order for all other species is maintained at the default values.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	FORD /Pt(S) 1.0/
	Stoichiometric coefficient	Required	--	FORD /Pt(S) 1.0/
	Reaction Example	`A1 + 8H(se) => 5H(se) + 6C(B) + 3open(se) + 4H2 + H 0.1 0.0 0.0` `FORD/H(se) 2.0/` `DCOL/2.46E-8/` `STICK`
	Notes	Multiple occurrences of the `FORD` construct may appear on the auxiliary line.
KPRODUCT	K-Product - K-product for reversible ionization reaction in liquid/aqueous phase – specifies the value of K-product as a function of temperature on which the reaction takes place. The definition of the K-product can be found in Given K-Product for Ion Dissociation Reactions in the Liquid Phase in the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Temperature polynomial coefficient	Required	--	KPRODUCT/1.0E-14 0.0 0.0 0.0/
	Temperature polynomial coefficient	Required	--	KPRODUCT/1.0E-14 0.0 0.0 0.0/
	Temperature polynomial coefficient	Required	--	KPRODUCT/1.0E-14 0.0 0.0 0.0/
	Temperature polynomial coefficient	Required	--	KPRODUCT/1.0E-14 0.0 0.0 0.0/
	Reaction Example	`HOCHO(aq) = H+ + HCO2- 3.6E06 0.0 0.0` `KPRODUCT /1.77e-04 0.2 0.003 -0.0001 /`
	Notes	The ionization reaction must be a liquid-phase reversible reaction and the product species must belong to the same phase. When more than one `KPRODUCT` keyword is given for a reaction, the parameters from the last one will be applied.
LANG	Langmuir-Hinshelwood Reaction Parameters - Indicates the use of the Langmuir-Hinshelwood rate expression. One auxiliary line should be supplied for each species appearing in the denominator of Equation 4–21 of the Chemkin Theory Manual . The keyword is followed, in slash delimited format, by the species name, the pre-exponential multiplier, the temperature factor, the enthalpy for the equilibrium constant, and the reaction order for that species (usually equal to one). The equilibrium constant is defined as , similar to the standard expression for rate constants.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	LANG /C6H6 1.26 0.0 0.0 1.0/
	Pre-exponential factor	Required	Depends on reaction	LANG /C6H6 1.26 0.0 0.0 1.0/
	Temperature exponent	Required	--	LANG /C6H6 1.26 0.0 0.0 1.0/
	Equilibrium enthalpy	Required	cal/mole	LANG /C6H6 1.26 0.0 0.0 1.0/
	Reaction order	Required	--	LANG /C6H6 1.26 0.0 0.0 1.0/
	Reaction Example	`C6H5CH3 + H2 => C6H6 + CH4` `2.507E-8 0.0 0.0 ! rate at 600C` `LANG /C6H6 1.26 0.0 0.0 1.0/` `LANG /C6H5CH3 1.01 0.0 0.0 1.0/` `LHDE /1/` `LHNU /C6H5CH3/` `LHPR /atm/`
	Notes	Only irreversible reactions are allowed with this option. Each species listed in a LHNU statement must have a `LANG` statement. Additional keywords LHDE , LHNU , and LHPR provide more flexibility in the form of the Langmuir-Hinshelwood or Eley-Rideal rate expressions.
LHDE	Langmuir-Hinshelwood Denominator Exponent Parameter - Allows the default value of 2 for the overall exponent for the denominator (m) to be overridden when LANG is used to specify a Langmuir-Hinshelwood rate expression. To specify an Eley-Rideal reaction, this keyword would be used and m set to 1. The use of any positive number is permitted, including real or fractional numbers.
	Parameters	Optional/Reqd.	Units	Examples
	Denominator exponent m	Required	--	LHDE /1/
	Reaction Example	`C6H5CH3 + H2 => C6H6 + CH4` `2.507E-8 0.0 0.0 ! rate at 600C` `LANG /C6H6 1.26 0.0 0.0 1.0/` `LANG /C6H5CH3 1.01 0.0 0.0 1.0/` `LHDE /1/` `LHNU /C6H5CH3/` `LHPR /atm/`
LHNU	Allows the explicit inclusion of equilibrium constants in the numerator of the LANG rate expression (the use of k rather than k', see Langmuir-Hinshelwood and Eley-Rideal Reactions of the Chemkin Theory Manual ) when LANG is used to specify a Langmuir-Hinshelwood rate expression. This keyword is followed by a slash delimited list of species names. For each species in the list, a multiplier of K will be applied to the rate constant.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	LHNU /C6H5CH3/
	Reaction Example	`C6H5CH3 + H2 => C6H6 + CH4` `2.507E-8 0.0 0.0 ! rate at 600C` `LANG /C6H6 1.26 0.0 0.0 1.0/` `LANG /C6H5CH3 1.01 0.0 0.0 1.0/` `LHDE /1/` `LHNU /C6H5CH3/` `LHPR /atm/`
	Notes	Each species listed in a `LHNU` statement must have a LANG statement.
LHPR	Indicates that the equilibrium constants are given in pressure units when LANG is used to specify a Langmuir-Hinshelwood rate expression. The LHPR keyword will affect the equilibrium constants for the specified reaction only; the reaction rate will still be assumed to be in the units specified on the `REACTIONS` line, or in the default moles, cm, and sec. The keyword is followed by the slash-delimited name of the pressure unit being used: ATM, BAR, TORR, PASC (for Pascals), or DYNE (for dynes per square cm), where the names are not case sensitive.
	Parameters	Optional/Reqd.	Units	Examples
	Pressure units character string	Required	--	LHPR /atm/
	Reaction Example	`C6H5CH3 + H2 => C6H6 + CH4` `2.507E-8 0.0 0.0 ! rate at 600C` `LANG /C6H6 1.26 0.0 0.0 1.0/` `LANG /C6H5CH3 1.01 0.0 0.0 1.0/` `LHDE /1/` `LHNU /C6H5CH3/` `LHPR /atm/`
MWOFF	Motz-Wise Correction - Turns off the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for a sticking-coefficient reaction.
	Reaction Example	`AR* => AR 1.0 0.0 0.0` `STICK` `MWOFF`
	Notes	By default, the Motz-Wise correction will be off for all sticking coefficient reactions; the default may be changed by including the keyword MWON on the `REACTIONS` line.
MWON	Motz-Wise Correction - Turns on the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for a sticking-coefficient reaction, superseding the default. By default the Motz-Wise will be off for all reactions using sticking coefficients unless the `MWON` keyword is given on the `REACTIONS` line, in which the new default will be to include the correction term.
	Reaction Example	`ALMe3 + O(S) => ALMe2(S) + 0.5C2H6 0.1 0.0 0.0` `STICK` `MWON`
	Notes	By default, the Motz-Wise correction will be off for all sticking coefficient reactions; the default may be changed by including the keyword `MWON` on the `REACTIONS` line.
NATIVE	Indicates the native species of a particle; see Native Surface Sites of the Chemkin Theory Manual .
NATIVE	Reaction Example	`OPEN(S) /NATIVE/`
NUCL	Supersedes the default rate calculation with the nucleation reaction rate expression; see Nucleation Reaction Data of the Chemkin Theory Manual .
NUCL	Reaction Example	`2A4 => 32C(B) + 20 H(se) + 28.72 open(se) 1.0E10 0.5 0.0` `NUCL`
REV	Reverse Reaction Parameters - Supersedes the reverse rates that would normally be computed through the equilibrium constant, Equation 3–6 of the Chemkin Theory Manual . `REV` must be followed by the three slash-delimited Arrhenius coefficients (, , and ) to specify the reverse rate.
	Parameters	Optional/Reqd.	Units	Examples
	Pre-exponential factor		Depends on reaction	REV /1.0E13 0.0 15000./
	Temperature exponent		--	REV /1.0E13 0.0 15000./
	Activation energy		cal/mole	REV /1.0E13 0.0 15000./
	Reaction Example	`C(S,R) + CH3 <=> D + CH3(S) 4.0E12 0.0 1200.0` `REV /1.0E13 0.0 15000./`
RORD	Arbitrary Reaction Orders - Supersedes the reverse reaction order for any species in the mechanism (with respect to species concentration), regardless of whether the species appears as a reactant or a product in the reaction. `RORD` must be followed by the slash-delimited species name and the new reaction order, and supersedes the values of in Equation 3–4 of the Chemkin Theory Manual pertaining to the particular species named on the line; the reaction order for all other species maintain their default values. Multiple occurrences of the `RORD` construct may appear on the auxiliary line.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	RORD /OH 2.0/
	Stoichiometric coefficient	Required	--	RORD /OH 2.0/
	Reaction Example	`H2+O2=2OH 0.170E+14 0.00 47780` `RORD /OH 2.0/`
	Notes	See also FORD .
STICK	Sticking Coefficients - The three coefficients given in the second field of the reaction line are to be interpreted as the parameters , , and in Equation 4–10 of the Chemkin Theory Manual for a sticking coefficient (rather than as a rate constant). There can be only one gas-phase reactant species in a sticking-coefficient reaction; moreover, its stoichiometric coefficient must be 1.
STICK	Reaction Example	`A1 + 8H(se) => 5H(se) + 6C(B) + 3open(se) + 4H2 + H 0.1 0.0 0.0` `FORD/H(se) 2.0/` `DCOL/2.46E-8/` `STICK`
UNITS	Unit Specifications for Reactions - Supersedes the current units for a particular reaction rate fit that may differ from the default units specified for other reaction expressions in the chemistry mechanism. `UNITS` must be followed by the slash-delimited character-string string, where string is one of the following (letters in brackets are optional): Parameters with energy units such as E _i : EVOL[TS], KELV[INS], CAL/[MOLE], KCAL[/MOLE], JOUL[ES/ MOLE], or KJOU[LES/MOLE]. Pre-exponential factors A _i : MOLE[S] or MOLEC[ULES], where the inclusion of `MOLEC` would indicate that the reaction rate expression is in units of molecules/cm³ rather than mole/cm³. ATM, BAR, PAS[CALS], DYN[ES], TOR[R] for pre-exponential factors , where the units of gas species are partial pressures. SITE[FR], where the units of surface species are site fractions and the rate units are 1/sec.
	Parameters	Optional/Reqd.	Units	Examples
	Reaction units character string	Required	--	UNITS /MOLECUES/
	Reaction Example	`CF3+ + E + #WSIO2(B) => #SIO2 + CF3 0.33 0.0 0.0` `BOHM !` `YIELD /0.01 20. 0.5 1.0/ UNITS/EVOLTS/`
	Notes	Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction. Default units for are cal/mole. Even if the default energy units are changed by giving the `UNITS` keyword, the temperature appearing in the Arrhenius expression of Equation 3–5 of the Chemkin Theory Manual , that is, in T raised to the power and in the denominator of the activation energy term, is still in Kelvins. If any of the units strings are given on the `REACTIONS` header line, it applies to all reactions, but may be superseded for a particular reaction by the auxiliary `UNITS` keyword. `UNITS` allows only one string parameter, but the user can repeat `UNITS` as many times as needed for a given reaction.
USRPROG	Optional User Rate Subroutine SKUPROG `-` The net rate-of-progress for the reaction will be obtained by calling a user-supplied subroutine, SKUPROG. An optional slash(/)-delimited integer parameter allows the user to select from more than one type of rate formulation. Wherever the net reaction rate is required, it will be obtained by calling the user-written subroutine. A template of SKUPROG is provided in the Ansys Chemkin installation, in the file sklib_user_routines.f located in the directory user_subroutines. Information about how to compile and link user routines into Chemkin is included in Chemkin Application Programming Interface Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Rate formulation type	Optional	--	USRPROG /1/
	Reaction Example	`CH3OH +H2O => CO2 + 3H2 1.0 0.00 0.0` `USRPROG/3/`
	Notes	`USRPROG` applies only to irreversible reactions, and cannot be used in conjunction with USRPROD (entered on the `REACTIONS` header line).
YIELD	Ion-energy-dependent Yield - Ion-enhanced reaction yield can be applied to a reaction using the following two steps. First, place a pound sign (#) in front of the species symbol (or stoichiometric coefficient if given) for each species that is subject to the ion-energy yield enhancement. The "sub-reaction" of species and coefficients demarcated with the # sign must satisfy mass, elemental, charge and site balance. Second, the auxiliary keyword `YIELD` must appear after the reaction, followed by the four parameters, h _yield, E _yield,0, t _i, and u _i (as described in Equation 4–33 of the Chemkin Theory Manual ). These parameters are included as a slash-delimited set following the `YIELD` auxiliary keyword. An example of a `YIELD` reaction is shown in Figure 4.7: Examples of Auxiliary Reaction Data .
	Parameters	Optional/Reqd.	Units	Examples
	Multiplicative factor h _yield	Required	Depends on reaction	YIELD /0.053 4.0 0.5 1.0/
	Energy threshold E _yield,0	Required	cal/mole	YIELD /0.053 4.0 0.5 1.0/
	Exponential constant t _i	Required	--	YIELD /0.053 4.0 0.5 1.0/
	Exponential constant u _i	Required	--	YIELD /0.053 4.0 0.5 1.0/
	Reaction Example	`CF3+ + E + #WSIO2(B) => #SIO2 + CF3 0.33 0.0 0.0` `BOHM !` `YIELD /0.01 20. 0.5 1.0/ UNITS/EVOLTS/`
	Notes	A reaction declared with ion-enhanced yield must contain one (and only one) positive ionic reactant species.

Note: Even if the default energy units are changed by giving one of the UNITS keyword, the temperature appearing in the Arrhenius expression of Equation 3–5 of the Chemkin Theory Manual , that is, in raised to the power and in the denominator of the activation energy term, is still in Kelvins.

Table 4.7: Auxiliary Keywords for Liquid Phase Reactions

Keyword	Definition
HENRY	Henry’s law for calculating equilibrium concentration levels in gas and liquid phases. Default form is dimension less. This can be changed by optional keyword `UNITS`.
	Reaction Example	`CO2 = CO2(aq) 1.0 0.0 0.` `VLE/HENRY 1 3.34e-05 2400 298.15 /`
	Notes	Four or five parameters may be provided following `HENRY`. The first parameter with an integer value of 1 or 2 indicates the type of temperature dependence for Henry's law. Value of 1, use the form: Here, , , are the three parameters input from following the first parameter. represents temperature in K. Value of 2, use the form: is the fifth parameter on the input line. This form is available only when pressure units are used specified for Henry's law using the keyword `UNITS`.
IDEAL	Raoult's law for calculating equilibrium concentrations in gas and liquid phases.
IDEAL	Reaction Example	`CO2 = CO2(aq) 1.0 0.0 0.` `VLE/ IDEAL/`
KMASS	Mass transfer coefficient used to calculate rate of mass exchange between two phases involving gas-liquid or liquid-liquid. This optional keyword follows the line with `VLE` inputs. Separate `KMASS` for product and reactant phase are specified. Units mass transfer coefficient are cm/s. The `KMASS` line can read in up to five parameters depending on the choice of model. The model is specified by the following keywords as the first parameter. `CONK`: Constant value of mass transfer coefficient. `CONDL`: Use two-film theory with constant diffusivity and length scale. `CONDT`: Use penetration theory with constant diffusivity and time scale. For `CONK`, mass transfer coefficient for that phase is specified by one value. Units are cm/s. For two-film and penetration theories, diffusivity is the first parameter with units of cm²/s. The last parameter is either film thickness (in cm) or contact time (in s). .
KMASS	Reaction Example	`o2(l) = o2 1.0 0.0 0.0` `VLE/ IDEAL/` `KMASS/ o2(l) CONDL 1.0e-4 0.01/` `KMASS/ o2 CONK 1.0e-3/` `REFSP/ o2/` `REFSP/ o2(l) /`
UNITS for Henry's Law	Form of the Henry's law can be changed using this additional keyword on the same line as `HENRY`. Units allowed are gas partial pressure in atm and pascal. In absence of this word, dimensionless form of Henry’s law is used.
	Reaction Example	`c6h12-1(l) = c6h12-1 1.0 0.0 0.` `VLE / HENRY 2 3.55e-5 2400. 298.15 / UNITS/MOLAR_ATM/`
	Notes	Allowed units for the gas phase concentrations are `MOLAR_PA, MOLAR_ATM, ATM, PA`. The first two form sconsider the units in (mole/m³)/Pa and (mole/m³)/atm, respectively. The latter two consider the partial pressure units in atm and Pa.
VLE	Vapor Liquid Equilibrium model for use with the phase transfer process. This requires additional parameters, `IDEAL` or `HENRY`, that specifies the model.
	Reaction Example	`c6h12-1(l) = c6h12-1 1.0 0.0 0.` `VLE / IDEAL /`
	Notes	Only one species on reactant and product side should be provided. This mapping is unique; a species may participate in only one `VLE` reaction.

4.5.3.1. Summary of Auxiliary Reaction Data

Any number of auxiliary information lines may follow a reaction line, in any order, and any number of keywords may appear on an auxiliary information line; however, an auxiliary keyword and its parameter(s) must appear on the same line.

Examples of auxiliary information are shown in Figure 4.7: Examples of Auxiliary Reaction Data . The above rules are summarized in Table 4.8: Summary of the Rules for Auxiliary Reaction Data .

Figure 4.7: Examples of Auxiliary Reaction Data

REACTIONS   KCAL/MOLE
! THE FOLLOWING ARE *CONTRIVED* EXAMPLES OF AUXILIARY KEYWORD USAGE
    SICL(S)  <=>  CL + SI(S)                               1.0E-3  0.0    2.
                                                           REV/1.0E13  0.0   37./
    CL + SICL(S) <=>  CL2 + SI(S)                          0.1     1.1   20.
          DUPLICATE   STICK  
          RORD /SI(S)  0/
    CL + SICL(S) <=>  CL2 + SI(S)                          1.4E11  0.0   15.
          DUPLICATE   COV/SICL(S)  -1.2  0.5  32./  FORD/CL+  1.0/
    CL*       =>  CL                                       1.0     0.0    0.
          STICK       MWOFF
    E + CL+ + SICL3(S) + SI(B) => SICL4 + SI(S)            0.50    0.0    0.
       BOHM
       ENRGDEP/1. 0.5 1.0/  UNITS/EVOLT/
    AR+ + E + #SIO2(D) => #SIO2  + AR                  1.0   0.0  0.0
       BOHM
       YIELD /0.023052 35. 0.5 1.0/ UNITS/EVOLTS/
    E + CL2+ + SICL3(S) + SI(B) => SICL4 + SICL(S)     0.50  0.0  0.0       FORD/ CL2+  2.43/
    C6H5CH3  +  H2 => C6H6 + CH4             1.4E-8   0.0     0.0   ! rate at 600C
       LANG /C6H6  1.26  0.0  0.0  1.0/
       LANG /C6H5CH3  1.01  0.0  0.0  1.0/
       LHDE /1/
       LHNU /C6H5CH3/
       LHPR /atm/

Figure 4.8: Examples of Auxiliary Reaction Data for Liquid Phase

nc12h26(l) = nc12h26    1.0  0.0  0. 
  VLE / IDEAL/                    !Use Raoult's law for ideal liquid
  KMASS/ nc12h26 (l) CONDL 1.0e-4  0.01/ 
  KMASS/ nc12h26      CONK 1.0e-3/
co2(l) = co2      1.0  0.0  0.
  VLE / HENRY  2  3.55e-05  2400.  298.15/

Table 4.8: Summary of the Rules for Auxiliary Reaction Data

Rule	Description
1	Auxiliary information lines may follow a reversible reaction to specify the reverse rate parameters explicitly; auxiliary information must follow any reactions that are duplicated.
2	Auxiliary keyword declarations may appear anywhere on the line, in any order.
3	Any number of auxiliary keywords may appear on a line, and more than one line may be used, but a keyword and its parameter(s) must appear on the same line.
4	Multiple keywords appearing on the same line must be separated by at least one blank space.
5	Any blank spaces between a keyword and the first slash are ignored and any blanks between the slashes and parameter(s) are also ignored. However, no blank spaces are allowed within a keyword or parameter.
6	The keyword `REV` followed by three slash-delimited Arrhenius coefficients may be used to specify the reverse rate parameters.
7	The keyword `DUPLICATE` (or `DUP`) must follow every occurrence of a duplicated reaction.
8	The keyword `STICK` indicates that the three coefficients on the reaction line are to be interpreted as the parameters a _i, b _i, and c _i in Equation 4–10 of the Chemkin Theory Manual . There must be exactly one gas-phase reactant species; its stoichiometric coefficient must be `1`.
9	The keyword `COV` is used to modify the forward rate constant by the expression in Equation 4–7 of the Chemkin Theory Manual . The word `COV` is followed by a surface species name and the three coverage parameters , and . The four entries after the word `COV` are slash-delimited.
10	The keyword `BOHM` indicates that the three coefficients on the reaction line are to be interpreted as the parameters a _i, b _i, and c _i in Equation 4–29 of the Chemkin Theory Manual ; the Bohm velocity correction is applied. There must be exactly one gas-phase reactant species and that species must be a positive ionic species; its stoichiometric coefficients must be `1`. Only irreversible reactions are allowed with this option. The electron must be declared in the list of species names in the Gas-phase Kinetics Pre-processor input.
11	The keyword `ENRGDEP` allows the rate constant to depend on ion energy according to Equation 4–30 of the Chemkin Theory Manual . The keyword is followed by the three parameters E _{ion, 0}, f _i, and g _i which are slash-delimited. There must be exactly one positive ionic reactant species in the reaction. Only irreversible reactions are allowed with this option.
12	The keywords `FORD` and `RORD` can be used to change the reaction order (with respect to species concentration) of the forward or reverse reaction, respectively, for any species in the mechanism, regardless of whether the species appears as a reactant or a product in the reaction. The species name and the new reaction order (slash-delimited) follow the keyword.
13	The `YIELD` keyword allows modification of the stoichiometric coefficients in a sub-reaction using the ion-yield option. The usage requires preceding each species in the sub-reaction (or its stoichiometric coefficient) with the pound sign (`#`). Following the reaction line, declare the `YIELD` keyword, then the four parameters h _yield, E _yield,0, t _i, and u _i of Equation 4–33 of the Chemkin Theory Manual , between slashes. There must be exactly one positive ionic reactant species in the reaction. Only irreversible reactions are allowed with this option. The sub-reaction demarcated with the `#` symbols must satisfy mass, elemental, charge and site balance. An example of the `YIELD` keyword appears in Figure 4.7: Examples of Auxiliary Reaction Data .
14	The `UNITS` keyword can be used to override the current default units for parameters with energy units or the pre-exponential factor for a given reaction. The usage is `UNITS/` string `/`, where string is one of the following: `EVOLTS`, `KELVINS`, `CAL/MOLE`, `KCAL/MOLE`, `JOULES/MOLE`, or `KJOULES/MOLE` (for parameters with energy units), or `MOLES` or `MOLECULES` (for pre-exponential factors).
15	The string `MWON` can be used to turn on the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual or the string `MWOFF` can be used to turn off this correction for a sticking coefficient reaction. Using the `MWOFF` or `MWON` keyword overrides the default option set up on the `REACTIONS` line or the default supplied by Surface Kinetics (which is `MWOFF`).
16	The `LANG` keyword can be used to input a Langmuir-Hinshelwood rate expression. The keyword is followed by a species name, three parameters giving the equilibrium constant, and a fourth parameter giving the order of that species in the reaction. Additional keywords `LHDE`, `LHNU`, and `LHPR` provide more flexibility in the form of the Langmuir-Hinshelwood or Eley-Rideal rate expressions.
17	The keyword `LHDE` allows the default value of 2 for the overall exponent for the denominator () to be overridden when `LANG` is used to specify a Langmuir-Hinshelwood rate expression. To specify an Eley-Rideal reaction, this keyword would be used to set to 1. The use of any positive number is permitted, including real or fractional numbers.
18	The keyword `LHNU` allows the explicit inclusion of equilibrium constants in the numerator of the `LH` rate expression (the use of rather than , see Langmuir-Hinshelwood and Eley-Rideal Reactions of the Chemkin Theory Manual ) when `LANG` is used to specify a Langmuir-Hinshelwood rate expression. This keyword is followed by a slash delimited list of species names. For each species in the list, a multiplier of will be applied to the rate constant. Each species listed in a `LHNU` statement must have a `LANG` statement.
19	The keyword `LHPR` indicates that the equilibrium constants are given in pressure units when `LANG` is used to specify a Langmuir-Hinshelwood rate expression. The `LHPR` keyword will affect the equilibrium constants for the specified reaction only; the reaction rate will still be assumed to be in the units specified on the `REACTIONS` line, or in the default moles, cm, and sec. The keyword is followed by the name of the pressure unit being used: atm, bar, torr, Pasc (for Pascals), or dyne (for dynes per square cm), where the names are not case sensitive.