4.5.1. REACTIONS Line Options

On the same line as the REACTIONS word, you may define certain options that will apply globally to all surface reactions. In some cases, Auxiliary Reaction Keywords given for a specific reaction may override these global settings. A summary of the REACTIONS -line options are provided in Table 4.3: Alphabetical Listing of REACTIONS-line Options for Surface Reaction Data.

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

Note: If units are not specified, and are assumed to be in (cm, mole, sec, K) and cal/mole, respectively.

Table 4.3: Alphabetical Listing of REACTIONS-line Options for Surface Reaction Data

Keyword	Definition
ATM	Supersedes the default units for all surface reactions that follow the `REACTIONS` header line for pre-exponential factors ; the units of gas species are partial pressures in atm.
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
BAR	Supersedes the default units for all surface reactions that follow the `REACTIONS` header line for pre-exponential factors ; the units of gas species are partial pressures in bar.
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
CAL/[MOLE]	Re-iterates the default units for all surface reactions that follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
DYN[ES]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for pre-exponential factors ; the units of gas species are partial pressures in dyne/cm².
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
EVOL[TS]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
JOUL[ES/MOLE]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
KCAL[/MOLE]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
KELV[INS]`KCAL/MOLE`	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
KJOU[LES/MOLE]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for parameters with energy units such as E _i.
Notes Default units for E _i are cal/mole.
MAXSP	Increases the maximum number of reactants or products allowed in a reaction. The number given by this keyword must be greater than the default limit of 6. For example, `REACTIONS MAXSP=11`.
Notes This keyword is available to both the gas-phase and surface reaction mechanism.
MOLEC[ULES]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for pre-exponential factors .
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
MOLE[S]	Re-iterates the default units for all surface reactions which follow the `REACTIONS` header line for pre-exponential factors .
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
MWOFF	Turns off the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for all sticking-coefficient reactions which follow the `REACTIONS` header line.
Notes By default, the Motz-Wise correction is off for all sticking coefficient reactions; the default may be superseded for a particular sticking-coefficient reaction by use of the auxiliary reaction keyword MWOFF or MWON .
MWON	Turns on the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for all sticking-coefficient reactions which follow the `REACTIONS` header line.
Notes By default, the Motz-Wise correction is off for all sticking coefficient reactions; the default may be superseded for a particular sticking-coefficient reaction by use of the auxiliary reaction keyword MWOFF or MWON .
NONCON	Allows non-conservation of sites in any surface reaction which follows the `REACTIONS` header line. Normally, any reaction that does not conserve the number of surface sites in each surface phase is considered to be in error; the inclusion of `NONCON` on the `REACTIONS` line supersedes that rule.
PAS[CALS]	Supersedes the default units for all surface reactions that follow the `REACTIONS` header line for pre-exponential factors ; the units of gas species are partial pressures in pascals.
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
SITE[FR]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for pre-exponential factors ; the units of surface species are site fraction and the reaction rate unit is 1/sec.
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
TOR[R]	Supersedes the default units for all surface reactions which follow the `REACTIONS` header line for pre-exponential factors ; the units of gas species are partial pressures in torr.
Notes Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.
USRPROD	The net rate-of-production for all species will be obtained by calling a user-supplied subroutine, `SKUPROD`. An optional slash(/)-delimited integer parameter allows the user to select from more than one type of rate formulation. Wherever the net rates of production of species are required, they will be obtained by calling the user-written subroutine. A template of `SKUPROD` 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 .
Notes `USRPROD` cannot be used in conjunction with USRPROG (entered after a particular reaction).

Keyword

Definition

ATM

Supersedes the default units for all surface reactions that follow the REACTIONS header line for pre-exponential factors ; the units of gas species are partial pressures in atm.

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

BAR

Supersedes the default units for all surface reactions that follow the REACTIONS header line for pre-exponential factors ; the units of gas species are partial pressures in bar.

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

CAL/[MOLE]

Re-iterates the default units for all surface reactions that follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

DYN[ES]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors ; the units of gas species are partial pressures in dyne/cm².

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

EVOL[TS]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

JOUL[ES/MOLE]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

KCAL[/MOLE]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

KELV[INS]KCAL/MOLE

Supersedes the default units for all surface reactions which follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

KJOU[LES/MOLE]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for parameters with energy units such as E _i.

Notes

Default units for E _i are cal/mole.

MAXSP

Increases the maximum number of reactants or products allowed in a reaction. The number given by this keyword must be greater than the default limit of 6. For example, REACTIONS MAXSP=11.

Notes

This keyword is available to both the gas-phase and surface reaction mechanism.

MOLEC[ULES]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors .

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

MOLE[S]

Re-iterates the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors .

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

MWOFF

Turns off the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for all sticking-coefficient reactions which follow the REACTIONS header line.

Notes

By default, the Motz-Wise correction is off for all sticking coefficient reactions; the default may be superseded for a particular sticking-coefficient reaction by use of the auxiliary reaction keyword MWOFF or MWON .

MWON

Turns on the Motz-Wise correction of Equation 4–15 of the Chemkin Theory Manual for all sticking-coefficient reactions which follow the REACTIONS header line.

Notes

NONCON

Allows non-conservation of sites in any surface reaction which follows the REACTIONS header line. Normally, any reaction that does not conserve the number of surface sites in each surface phase is considered to be in error; the inclusion of NONCON on the REACTIONS line supersedes that rule.

PAS[CALS]

Supersedes the default units for all surface reactions that follow the REACTIONS header line for pre-exponential factors ; the units of gas species are partial pressures in pascals.

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

SITE[FR]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors ; the units of surface species are site fraction and the reaction rate unit is 1/sec.

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

TOR[R]

Supersedes the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors ; the units of gas species are partial pressures in torr.

Notes

Default units for are cgs (cm, sec, K, mole), the exact units depending on the order of the reaction.

USRPROD

The net rate-of-production for all species will be obtained by calling a user-supplied subroutine, SKUPROD. An optional slash(/)-delimited integer parameter allows the user to select from more than one type of rate formulation. Wherever the net rates of production of species are required, they will be obtained by calling the user-written subroutine. A template of SKUPROD 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 .

Notes

USRPROD cannot be used in conjunction with USRPROG (entered after a particular reaction).

Note: Chemkin does not support user-written programs, so you are cautioned to use the SKUPROD user routine feature at your own risk. Also, there are some features in the program executables that will be incompatible with the global replacement of species rates of production, such as sensitivity analysis and rate-of-production analysis. Such features will return zero values when user-rate programming is encountered.